01 atoms molecules stoichiometry - yellowreef · 2013. 9. 16. · (iii) no . answer keys: 2 ......

Chemistry - Challenging Drill Questions themis

1 - 10

Answer keys:

MCQs

07ZZ01-1-M-01 A

07ZZ01-1-M-02 A

07ZZ01-1-M-03 D

07ZZ01-1-M-04 A

07ZZ01-1-M-05 C

07ZZ01-1-M-06 B Questions

07ZZ01-1-Q-01

(a) 87.9

(b)(ii) acid not an ideal gas

(iii) small peak is result of dimer

(c)(i) 114, 116 and 118

(ii) 116, result of 2 species

MCQs

07ZZ01-2-M-01 D

07ZZ01-2-M-02 B

07ZZ01-2-M-03 D

07ZZ01-2-M-04 D

07ZZ01-2-M-05 A

07ZZ01-2-M-06 B

MCQs

07ZZ01-3-M-01 C

07ZZ01-3-M-02 B

07ZZ01-3-M-03 C

07ZZ01-3-M-04 D

07ZZ01-3-M-05 B

Questions

07ZZ01-3-Q-01

(a) N2O3

(c) 30 [NO]+; 46 [NO2]+; 60 [N2O2]+

(d) 6.84 105 Pa

(e) Ideal gas behaviour

MCQs

07ZZ01-4-M-01 B

07ZZ01-4-M-02 B

07ZZ01-4-M-03 B

07ZZ01-4-M-04 A

07ZZ01-4-M-05 C

07ZZ01-4-M-06 A

07ZZ01-4-M-07 C

07ZZ01-4-M-08 C

07ZZ01-4-M-09 C

07ZZ01-4-M-10 C

Questions

07ZZ01-4-Q-01

(a)(i) H3AsO4 2I 2H

H3AsO3 I2 H2O

(ii) 20.1

(b)(i) 106.3

(ii) X ClFO3

(iii) No

2 atomic structure

2 - 11

Answer keys:

MCQs

07ZZ02-1-M-01 D

07ZZ02-1-M-02 A

07ZZ02-1-M-03 D

07ZZ02-1-M-04 A

07ZZ02-1-M-05 D

07ZZ02-1-M-06 A

07ZZ02-1-M-07 B Questions

07ZZ02-1-Q-01

(i) One of two or more atoms having the same atomic

number but different mass numbers; Isotope of iodine A and D

(ii) Charge to mass ratio of the ions of the two isotopes does not differ significantly.

07ZZ02-2-M-01 C

07ZZ02-2-M-02 D

07ZZ02-2-M-03 D

07ZZ02-2-M-04 B

07ZZ02-2-M-05 A

07ZZ02-2-M-06 D

07ZZ02-2-M-07 B

07ZZ02-2-M-08 D

07ZZ02-2-M-09 D

07ZZ02-2-M-10 A

07ZZ02-2-M-11 C

07ZZ02-2-M-12 A

07ZZ02-2-M-13 C

07ZZ02-2-M-14 D

07ZZ02-2-M-15 D

07ZZ02-2-M-16 D

07ZZ02-2-M-17 D

07ZZ02-2-M-18 C

07ZZ02-2-M-19 D

07ZZ02-2-M-20 D

07ZZ02-2-M-21 A

07ZZ02-2-M-22 B

Questions

07ZZ02-2-Q-01

(a)(i) Group V. 1s2 2s2 2p6 3s2 3p3

(iii) Pair I: P and X, Group VI; Pair II: Q and Y, Group VII

(iv) S : 1s2 2s2 2p6; T : 1s2 2s2 2p6 3s1

(b)(ii) m/e 15

07ZZ02-2-Q-02

(a) Tc6+

07ZZ02-2-Q-03

(b)(i) 1s22s22p63s23p63d104s24p6

(ii) Ionic size of Y is larger than that of Rb ; nuclear

charge of Y is smaller than that of Rb

(c)(i) First IE of X is lower than P

(ii) First IE of X is higher than that of Se

(d) X forms covalent bonds with F2. Mg forms an ionic compound with F2. Enthalpy change of reaction is highly endothermic.

07ZZ02-2-Q-04

(a)(i) More energy is required to remove electron from an increasingly positive ion.

(ii) A large amount of energy is required to remove the 6th electron

(b)(ii) NaN3 is soluble in water; NaClO2 is soluble in water

3 chemical bonding

3 - 15

Answer keys: MCQ 07ZZ03-1-M-01 A

07ZZ03-1-M-02 D

07ZZ03-1-M-03 B

07ZZ03-1-M-04 A

07ZZ03-1-M-05 B

07ZZ03-1-M-06 C

07ZZ03-1-M-07 B

07ZZ03-1-M-08 A

07ZZ03-1-M-09 C

07ZZ03-1-M-10 B

07ZZ03-1-M-11 B

07ZZ03-1-M-12 D

07ZZ03-1-M-13 A

07ZZ03-1-M-14 D

07ZZ03-1-M-15 A

07ZZ03-1-M-16 D

07ZZ03-1-M-17 B

07ZZ03-1-M-18 A

07ZZ03-1-M-19 A

07ZZ03-1-M-20 C

07ZZ03-1-M-21 D

07ZZ03-1-M-22 A

07ZZ03-1-M-23 C

07ZZ03-1-M-24 D

07ZZ03-1-M-25 D

07ZZ03-1-M-26 B

07ZZ03-1-M-27 D

07ZZ03-1-M-28 D

07ZZ03-1-M-29 B

07ZZ03-1-M-30 C

07ZZ03-1-M-31 B

07ZZ03-1-M-32 B

07ZZ03-1-M-33 A

07ZZ03-1-M-34 B

07ZZ03-1-M-35 C

07ZZ03-1-M-36 C

07ZZ03-1-M-37 D

07ZZ03-1-M-38 C

07ZZ03-1-M-39 A

07ZZ03-1-M-40 C

07ZZ03-1-M-41 B

07ZZ03-1-M-42 D

07ZZ03-1-M-43 B

07ZZ03-1-M-44 A

07ZZ03-1-M-45 B

07ZZ03-1-M-46 C

07ZZ03-1-M-47 B

07ZZ03-1-M-48 D

07ZZ03-1-M-49 A

Questions 07ZZ03-1-Q-01

W - giant metallic structure

X - giant ionic structure

Y - simple molecular structure

Z - giant molecular structure 07ZZ03-1-Q-02

(a) Both are non-polar

(b) Both NaF and CsCl are ionic compounds

(c) Shapes of molecules are dependent on number of bond pairs and lone pairs of electrons around the central atom

(d) Ammonia is able to form hydrogen bonding between its molecules and water molecules 07ZZ03-1-Q-03

(a) N2H4: three bond pairs and 1 lone pair around each N, trigonal pyramidal

around each N, bond angle

of HNH or HNN 107°

N2O4: three bond pairs and no lone pair around each N, trigonal planar around each N, bond angle of

ONO or ONN 120°

(b) H2O and NH3: simple molecular structure, discrete covalent molecules held together by relatively strong intermolecular hydrogen bonds

HCl and CH4: simple molecular structure, discrete covalent molecules held together by weaker intermolecular van der Waals’ forces 07ZZ03-1-Q-04

(a) BF3: strong covalent bonding within molecule; simple discrete molecules held by weak van der Waals’ forces

AlF3: ionic bonding, strong electrostatic attraction between positively charged cations and negatively charged anions in a giant ionic structure

(b) Dative covalent bond. 07ZZ03-1-Q-05

(a) XeF2: linear; XeF4: square planar

(b) Besides intermolecular forces, melting is also dependent on how close the molecules are packed together in the solid state

(c)(i) Noble gases all have paired electrons. To react to form covalent compounds, the noble gases need to promote electrons up to empty orbitals of higher energy so that single electrons are present

(ii) The formation of XeF bond, which is stronger than Xe-I bond due to a larger electronegativity difference, compensates for energy needed to promote electrons to orbitals of higher energy level.


4 - 10

Answer keys: MCQ 07ZZ04-1-M-01 D

07ZZ04-1-M-02 D

07ZZ04-1-M-03 A

07ZZ04-1-M-04 A

07ZZ04-1-M-05 A

07ZZ04-1-M-06 A

07ZZ04-1-M-07 B

07ZZ04-1-M-08 C

07ZZ04-1-M-09 D

07ZZ04-1-M-10 B

07ZZ04-1-M-11 A

07ZZ04-1-M-12 C

07ZZ04-1-M-13 D

07ZZ04-1-M-14 A

07ZZ04-1-M-15 C

07ZZ04-1-M-16 D

07ZZ04-1-M-17 B

07ZZ04-1-M-18 D

07ZZ04-1-M-19 A


(a)(i) 70.0

(ii) 70

(iii) X shows a stronger deviation from ideal gas behavior and strong pd-pd forces of attraction

(iv) CF3, CHF2

, CF2, CF, C

(b)(i) F2 2I 2F I2,

2S2O32 I2 2I S4O6

2

(ii) 115 cm3

07ZZ04-1-Q-02

(a) Shape: pyramidal; Bond angle: 107o

(b)(i) Ca(OH)2 2NH4Cl

CaCl2 2NH3 2H2O

(ii) 2.59g

07ZZ04-1-Q-03

(a) Mg(NO3)2 MgO

2NO2 ½O2

(b)(i) 0.01706

(ii) 8.50 103

(iii) NaNO3(s) NaNO2 (s)

½O2 (g)

(iv) 53.8 cm3

(v) High temperature and low pressure

07ZZ04-1-Q-04

(a) ¼

(b) Strong forces of attraction reduce the force of impact of the molecules on the vessel walls

07ZZ04-1-Q-05

(b)(i) N2H4(l) N2(g)

4H(aq) 4e (anode);

NO3(aq) 4H(aq) 3e

NO(g) 2H2O(l) (cathode)

(ii) 1.47 V

(iii) thermodynamically feasible but kinetically not feasible

(iv) Eoxidation decreases;

overall Ecell increases

(c)(i) High temperature and low pressure

(iii) The volume of N2H4 is less than that of an ideal gas

07ZZ04-1-Q-06

(a)(ii) The deviation is due to significant intermolecular attractions between gas particles

(b)(i) [CH279

BrCH279

Br]+, 1/4;

[CH279

BrCH281

Br]+, 1/2;

[CH281

BrCH281

Br]+, 1/4

(ii) The peak was due to the formation of the cyclic bromonium intermediate

(iii) The intermediate species are unstable

07ZZ04-1-Q-07

(a)(i) 1

(b)(i) Down the group, attractive forces between the atoms become stronger due to larger atomic size as a result of more electrons. The gas volume is negligible compared to the space occupied by the gas becomes less valid

(ii) High temperature and low pressure

(c)(ii) Intramolecular – 2 double covalent bonds. Intermolecular – non-polar, id-id forces of attraction

07ZZ04-1-Q-08

(a) Low temperature and high pressure

(b)(i) 100

(ii) sample D is dimmers; sample A is monomers; samples B and C is a mixture of monomers and dimmers

(iii) hydrogen bonding

07ZZ04-1-Q-09

(a)(i) higher pressure causes formation of hydrogen bonds; the gas is no longer ideal

(ii) The volume drops sharply as gaseous ammonia changes into liquid

(iii) The particles are closely packed together in a liquid

(b)(i) 0.711 atm

(ii) 30.8 atm2


5 - 20

Answer keys:

MCQs 07ZZ05-1-M -01 A

07ZZ05-1-M -02 B

07ZZ05-1-M -03 A

07ZZ05-1-M -04 D

07ZZ05-1-M -05 B

07ZZ05-1-M -06 C

07ZZ05-1-M -07 D

07ZZ05-1-M -08 C

07ZZ05-1-M -09 B

07ZZ05-1-M -10 B

07ZZ05-1-M -11 B

07ZZ05-1-M -12 A

07ZZ05-1-M -13 A

07ZZ05-1-M -14 C

07ZZ05-1-M -15 D

07ZZ05-1-M -16 A

07ZZ05-1-M -17 B

07ZZ05-1-M -18 C

07ZZ05-1-M -19 B

07ZZ05-1-M -20 B

07ZZ05-1-M -21 C

07ZZ05-1-M -22 A

07ZZ05-1-M -23 D

07ZZ05-1-M -24 C

07ZZ05-1-M -25 D

07ZZ05-1-M -26 C

07ZZ05-1-M -27 B

07ZZ05-1-M -28 D

07ZZ05-1-M -29 A

07ZZ05-1-M -30 B

07ZZ05-1-M -31 A

07ZZ05-1-M -32 A

07ZZ05-1-M -33 B

07ZZ05-1-M -34 B


(a) 9.49 kg

(b)(i) C4H10 92

O2 4CO

5H2O

(ii) 283 kJ mol1 ; 1745

kJ mol1

(iii) 1130 kJ mol1

(iv) carbon monoxide contains a triple bond

07ZZ05-1-Q-02

(a) Lattice energy is the enthalpy change when one mole of solid zinc chloride is formed from its constituent gaseous zinc and chloride ions at 298 K and 1 atm pressure

(c) 2772 kJ mol1

(d) The melting point of zinc chloride will be lower than that of zinc bromide. Zinc chloride has a covalent character though it is an ionic solid

07ZZ05-1-Q-03

(a) The standard enthalpy change of formation of a substance is the enthalpy change when one mole of the substance is formed from its constituent elements in their standard states at 298K and 1 atm pressure

(b)(iii) 435 kJ mol1

(iv) 14 kJ mol1

(c) the energy released during hydration is not enough to break the ionic bonds in potassium chloride, making it less soluble in water

07ZZ05-1-Q-04

(a)(i) 791 kJ mol1

(ii) 73.5 kJ mol1

(b) Hvap increases from chlorine to bromine to iodine. It is a measure of intermolecular forces

07ZZ05-1-Q-05

(a)(i) 4.76 103 kJ mol1

(ii) 4428 kJ mol1

(b) HCl is a strong monobasic acid; H2SO4 is a strong dibasic acid; both undergo full dissociation in aqueous solution. CH3COOH is a weak monobasic acid, undergoes partial dissociation in aqueous solution

07ZZ05-1-Q-06

(a)(i) C8H18 (l) 25

2O2 (g)

8CO2 (g) 9H2O (l)

(ii) 47.9 kJ g1; 29.7 kJ g1

(iii) octane: (advantage) releases more energy per gram of fuel. (disadvantage) requires more sophisticated equipment to refine; ethanol: (advantage) simpler to manufacture. (disadvantage) releases less energy per gram of fuel

07ZZ05-1-Q-07

(a)(ii) 1560 kJ mol1

(iii) The magnitude of lattice energy would decrease for caesium phosphate

(b)(i) Hc(N2) 2

Hf(NO2)

(ii) 1331 kJ mol1

07ZZ05-1-Q-08

(a)(ii) 30 kJ mol1

(b)(i) 2220 kJ mol1

(ii) 45.3C

07ZZ05-1-Q-09

(a)(i) 320 kJ mol1

(ii) Covalent character in the ionic bond causes experimental lattice energy to be more exothermic

(b)(i) 2.25 g

(ii) PbCl2 is the white ppt, while PbI2 is the yellow ppt. PbI2 has lower solubility. Ionic

product [Pb2][Cl] decreases below its Ksp and white ppt dissolves

07ZZ05-1-Q-10

(a)(i) The standard enthalpy change when 1 mole of ethyne is completely burnt in oxygen under standard conditions

(ii) 1300 kJ mol1

(iii) 175 kJ mol1

(b) 562 kJ mol1

07ZZ05-1-Q-11

(a) 416 kJ mol1

(b)(i) CH3COOH(aq)

KOH(aq)

CH3COOK(aq) H2O(l)

(ii) 52.5 kJ mol1

(iii) The reaction between hydrochloric acid with potassium hydroxide is more exothermic as a strong acid and a strong base completely ionize in dilute solutions

5 chemical energetics

5 - 21

07ZZ05-1-Q-12

(a) Standard enthalpy change of formation is defined as the heat change when 1 mol of a substance is formed from its elements in their standard states under standard conditions. Standard enthalpy change of atomization is defined as the heat change when 1 mol of gaseous atoms of the element is formed from its element under standard conditions

(b) 802.5 kJ mol1

(c) The carbon-oxygen bond in CO is a triple bond whereas that in CO2 is a double bond

(d) 0.211 mol

07ZZ05-1-Q-13

(a) The enthalpy change of formation of magnesium oxide is the enthalpy change when one mole of MgO(s) is completely formed from Mg(s) and O2(g)

(b)(i) 41.0C

(ii) 426 kJ mol1

(iii) 589 kJ mol1

(iv) The magnitude of the enthalpy change of reaction will be smaller

07ZZ05-1-Q-14

(a) They have similar first ionization energies

(b)(i) Lattice energy is the heat evolved when one mole of ionic compound is formed from its gaseous ions under standard conditions

(b)(ii) 0 kJ mol1

c) The first ionization energy of neon is too high to form an ionic compound. Neon is unable to expand its octet structure to form a covalent compound

07ZZ05-1-Q-15

(a)(i) the mean bond energy is an average obtained from a full range of molecules containing that particular bond

(ii) ¼CH4(g) ¼C(g) H(g)

(iii) 278 kJ mol1

(b) a lot of energy is required to overcome strong covalent bonds joining the carbon atoms

(c)(i) 120

(ii) σ-bond : head-on overlap of 2 sp2

orbitals of C atoms; -bond : side on overlap of 2 p orbitals

(iii) The bond energy of a

-bond is less than that of a σ-bond

07ZZ05-1-Q-16

(a)(i) C (s) 2H2 (g) ½O2

(g) CH3OH

(ii) 238.8 kJ mol1

(iii) 128.3 kJ mol1

(b)(i) 64.4 mol

(ii) 1.87 kg

(iii) 1.85 g

(iv) More propane needs to be burnt due to heat loss

07ZZ05-1-Q-17

(a)(i) B2H6(g) 3O2(g)

B2O3(s) 3H2O(l)

(ii) 2167 kJ mol1

(b)(i) 19027 kJ mol1

(c) 649 kJ mol1

07ZZ05-1-Q-18

(a) 240.6 kJ mol1

(b)(i) 3285 kJ mol1

(ii) 3140 kJ mol1

(iii) Bond energies are average values which may not be the same as those values which are unique to CH3COOH

07ZZ05-1-Q-19

(a)(i) The standard enthalpy change of formation of XeF4 is the enthalpy change when one mole of xenon fluoride is formed from its elements, xenon and fluorine under standard conditions

(ii) XeF4(g) 2H2(g) fH

Xe(g) 4HF(g)

(iii) 847 kJ mol1

(iv) 136 kJ mol1

(b)(i) 624 kJ mol1

(ii) 57 kJ mol1

07ZZ05-1-Q-20

(a)(i) Upon combustion, hydrogen gives only water that is non-polluting

(ii) CH4 gives more energy upon combustion since both CO2 and H2O are produced whereas combustion of hydrogen only gives H2O

(b)(i) 242 kJ

(ii) Enthalpy change of vaporization of water

(c) Slow release of hydrogen

07ZZ05-1-Q-21

(i) NH4NO3(s) N2(g)

2H2O(g) ½O2(g)

(ii) 154 kJ mol1

(iii) The enthalpy change of decomposition is relatively exothermic; products are gaseous resulting in great expansion of volume

07ZZ05-1-Q-22

(a)(ii) 31.0 kJ mol1

(b)(i) Both HCl and HNO3 are strong acids which ionize completely.

Therefore, the Hneu for both acids is the same. H2SO4 is a strong dibasic acid which forms 2 moles of water. Therefore, the enthalpy change is twice that of HCl and HNO3. Ethanoic acid is a weak acid which ionizes only partially. The enthalpy change is less exothermic than expected.

(ii) NO2 has 2 groups of

electron clouds and no lone pair surrounds the central N atom.

NO2 has 2 groups of

electron clouds and one lone pair surrounds the central N atom

07ZZ05-1-Q-23

(a)(i) 26 kJ mol1

(ii) 0.79C

(iii) Heat is gained from the surrounding so that temperature obtained is higher

(b) NH4 tetrahedral

(109); NH2 bent

(104)


5 - 22

07ZZ05-1-Q-24

(a)(i) 2877 kJ mol1

(ii) butene 48.5 kJ g1 ;

butane 49.6 kJ g1; As hydrogen content increases, fuel value in hydrocarbon also increases

07ZZ05-1-Q-25

(a)(ii) 57.1 kJ mol1

(iii) 99.4 kJ mol1

(b)(ii) 132 kJ mol1

(iii) The enthalpy change of hydration of the calcium ion is lower than that of magnesium

07ZZ05-1-Q-26

(a) The enthalpy change of solution of MgF2 is the enthalpy change when one mole of MgF2 is completely dissolved in a solvent to form an infinitely dilute solution at 298 K and 1 atm pressure

(b)(i) 2805 kJ mol1

(ii) 457 kJ mol1

(iii) Ht of NaBr will be less exothermic than MgF2

07ZZ05-1-Q-27

(i) Weak van der Waals’ forces of attraction exist between chlorine molecules while stronger metallic bonding exists between sodium atoms

(ii) Copper has stronger metallic bonds which require more energy to break as compared to sodium

(iii) The breaking of ionic bonds present in sodium chloride is

easier compared to the stronger metallic bonds present in a transition element like copper


6 - 26

Answer keys:

MCQs

07ZZ06-1-M-01 A

07ZZ06-1-M-02 B

07ZZ06-1-M-03 B

07ZZ06-1-M-04 C

07ZZ06-1-M-05 D

07ZZ06-1-M-06 C

07ZZ06-1-M-07 D

07ZZ06-1-M-08 C

07ZZ06-1-M-09 B

07ZZ06-1-M-10 B


(a) 2NO2 H2O HNO2

NO3 H; Yes, the

reaction will occur

(b) Half-equation: BrO3

6H 6e Br

3H2O, 2I I2 2e; Overall equation:

BrO3 6H 6I

3I2 Br 3H2O

07ZZ06-2-M-01 C

07ZZ06-2-M-02 B

07ZZ06-2-M-03 D

07ZZ06-2-M-04 A

07ZZ06-2-M-05 B

07ZZ06-2-M-06 D

07ZZ06-2-M-07 C

07ZZ06-2-M-08 C

07ZZ06-2-M-09 C

07ZZ06-2-M-10 A

07ZZ06-2-M-11 C

07ZZ06-2-M-12 B

07ZZ06-2-M-13 C

07ZZ06-2-M-14 B

07ZZ06-2-M-15 C

07ZZ06-2-M-16 D

07ZZ06-2-M-17 B

07ZZ06-2-M-18 D

07ZZ06-2-M-19 B

07ZZ06-2-M-20 C

07ZZ06-2-M-21 D


(a)(i) 2Cu Cu Cu2

(ii) Disproportionation reaction

(iii) Ecell 0.52 0.15

0.37V > 0; feasible

(b)(ii) 0.83 V

07ZZ06-2-Q-02

(a)(i) Zn Zn2 2e; O2

2H2O 4e 4OH;

2Zn O2 2H2O 2Zn(OH)2

(ii) 1.16V

(iii) The position of equilibrium of the overall reaction shifts right as zinc hydroxide dissolves. The EMF thus increases

(iv) 12 years

(b)(i) 0.28V

(ii) The concentration of

Cu2 in the two half-cells is equal

07ZZ06-2-Q-03

(a) 2Cl Cl2 2e

(b) FeCl2

(c) Fe2 2Cl Fe Cl2

(d) 0.223 dm3

(e) 2.27A

07ZZ06-2-Q-04

(a)(i) CH4 2H2O CO2

8H 8e

(ii) O2 4H 4e 2H2O

(b) This will increase the overall EMF of the cell. Increasing the concentration of oxygen at the cathode will shift the equilibrium to the right

(c) 19.2 dm3

(d) Efficient and produces water as useful product

07ZZ06-2-Q-05

(b)(i) O2 2H2O 4e

4OH; 2Fe O2 2H2O

2Fe2 4OH

(ii) 0.84V

(iii) 2Fe3 6OH

Fe2O3.3H2O

(iv) Painting and oiling

07ZZ06-2-Q-06

(a)(i) 0.76V

(ii) from the X electrode to the lead electrode

(iii) Ecell decreases

(b)(i) 2Cl(aq) Cl2(g)

2e; 2H2O(l) 2e

H2(g) 2OH(aq)

(ii) 2H2O(l) 2NaOH(aq)

Cl2(g) H2(g) 2NaOH(aq)

(iii) 1.50 107 C

(iv) 3.73 103 dm3

07ZZ06-2-Q-07

(a)(i) 2OH(aq) Cl2(aq)

Cl(aq) ClO(aq)

H2O(l)

(ii) 3ClO(aq) ClO3(aq)

2Cl(aq); Disproportionation is a

change in which one particular molecule, ion or atom is simultaneously oxidized and reduced

(b) Hydrogen ions are preferentially discharged as compared to sodium ions, thus no sodium metal can be obtained

07ZZ06-2-Q-08

(a) H2 2OH 2H2O

2e; O2 2H2O 4e

4OH

(b)(i) 9.854g

(ii) 0.0173 cm

(iii) Since the redox potential of magnesium is more negative than that of nickel, it is unlikely to be reduced at the cathode

07ZZ06-2-Q-09

(a) The potential difference between a standard hydrogen electrode and a metal immersed in a solution containing metal ions at standard conditions

of 1 mol dm3 at 298K and 1 atm pressure

(c)(i) Cu2(aq) 2e

Cu(s); Cu(s) Cu2(aq)

2e

(ii) 1.01A

(iii) Conditions of electrolysis may not be standard

07ZZ06-2-Q-10

(a)(i) Pb2 2e Pb; Pb2

2H2O PbO2 4H

2e

(ii) 3860 s

(b) 1.60V; PbO2(s) Pb(s)

4H(aq) Pb2(aq) 2H2O(l)

6 electrochemistry

6 - 27

c)(i) During charging, Pb2

and Zn2 undergo reduction

(ii) During discharging,

PbO2 and Zn2 undergo reduction

07ZZ06-2-Q-11

(a)(i) 4Al 3O2 6H2O

4Al(OH)3; 2.70V

(ii) Negative electrode since oxidation occurs

(iii)(1) Concentration of solid is constant. No change in cell EMF

(2) The redox potential becomes more positive. EMF will increase

(b)(i) The positive electrode as oxidation occurs at the anode of an electrolytic cell

(ii) 2.00 103

(iii) 6.00 103

(iv) 3

07ZZ06-2-Q-12

(a)(i) 0.90V

(ii) Pb(s) 2Fe3(aq)

Pb2(aq) 2Fe2(aq)

(iv) Pb2 will be reduced to

Pb; Cr2 will be

oxidized to Cr3

(b)(i) Pb2(l) O2(l)

½O2(g) Pb(l)

(ii) 8.07 cm3

07ZZ06-2-Q-13

(a) Standard electrode potential is defined as the potential difference between a standard hydrogen electrode and a metal which is immersed in a solution containing metal ions at 1 mol

dm3 concentration at 25oC and 1 atm pressure

(b) Ecell increases by becoming more positive

(c)(i) 2Fe3 Cu Fe2

Cu2

(ii) 0.43V

(d)(i) 7.50 103

(ii) 0.238g

07ZZ06-2-Q-14

(i) Zn Zn2 2e ; O2

4H 4e 2H2O

(ii) 2Zn O2 4H

2Zn2 2H2O

(iii) 1.99V

(iv) 15.2 yrs

07ZZ06-2-Q-15

(a)(i) Standard electrode potential is reduction potential set up when an electrode is in contact with a solution of its ions of concentration 1 mol

dm3 at 298K and 1 atm pressure. The reduction potential is measured with respect to the standard hydrogen electrode

(iii) redox potential of

X2/X and Y2/Y are

0.23V and 0.34V respectively

(iv) 0.57V

(b)(i) Pb PbO2 2H2SO4

2PbSO4 2H2O;

12.3V

(ii) when an external source of direct current is applied, it will recharge the battery by driving the cell reaction in the reverse direction

(iii) Sulphuric acid is consumed during discharging to form solid PbSO4 and water

07ZZ06-3-M-01 A

07ZZ06-3-M-02 D

07ZZ06-3-M-03 B

07ZZ06-3-M-04 B

07ZZ06-3-M-05 C

07ZZ06-3-M-06 B

07ZZ06-3-M-07 B

07ZZ06-3-M-08 A

07ZZ06-3-M-09 B

07ZZ06-3-M-10 A

07ZZ06-3-M-11 D

07ZZ06-3-M-12 B

07ZZ06-3-M-13 B

07ZZ06-3-M-14 D

07ZZ06-3-M-15 B

07ZZ06-3-M-16 C

07ZZ06-3-M-17 B

07ZZ06-3-M-18 A

07ZZ06-3-M-19 D

07ZZ06-3-M-20 B


(a)(i) 0.83V; M3 undergoes reduction and thus makes up the positive electrode in the set-up

(ii) The cell EMF will increase as adding water will cause the

concentration of Ni2 to decrease, and the equilibrium to shift to the left

(b)(i) Ni Ni2 2e; Ni2

2e Ni

(ii) 8790s

(iii) It may be due to the resistance in the wire or battery

07ZZ06-3-Q-02

(a) 2.26 hrs

(b)(i) oxidation occurred at

the M electrode. E

(M2/M) is negative

(0.30V); reduction occurred at the L

electrode. E (L2/L) is

positive (0.45V)

(ii) 0.75V

07ZZ06-3-Q-03

(a)(i) 2Br (l) Br2(g)

2e; Sr2(l) 2e Sr(l)

(ii) An atmosphere of argon provides an inert environment to prevent oxidation of strontium

(iii) 8.81 104 s

(iv) H(aq) will be preferentially reduced to hydrogen gas and

not Sr2

(b)(i) 2Co3 2Cl 2Co2

Cl2; 0.46V

(ii) 2Cr2 H2O2 2H

2Cr3 2H2O; 2.18V

07ZZ06-3-Q-04

(a)(i) Rust is an ionic compound which is brittle in nature

(ii)(I) A: Fe Fe2 2e; C:

O2 2H2O 4e

4OH

(ii)(II) Electrons flow from A to C

(ii)(III) Most rust would accumulate near where the surface of the water meets air

(iii) Fe preferentially undergoes oxidation

to form Fe2 while O2 undergoes reduction

to form OH; 0.84V

(b)(i) Cans for soft drinks

(ii) The diagram would consist of dilute


6 - 28

H2SO4(aq) electrolyte, an aluminium anode and a graphite cathode connected by a cell in external circuit

07ZZ06-3-Q-05

(a) Terminal Y is negative. Electrons which are produced by oxidation of aluminum leave via terminal Y

(b) O2(g) 2H2O(l) 4e

4OH(aq)

(c) Electrode Z must be porous so that oxygen may diffuse through the electrode and reach the electrolyte to be reduced

(d) Water may be reduced at electrode Z instead of oxygen to form hydrogen gas. H2(g) formed in the sealed container is potentially explosive

(e) Ordinary aluminum has a dense, protective layer of aluminum oxide which is impervious. This layer prevents oxidation, hence it cannot be used as an anode

(f) Al produces more electrons per mole of metal, so more electrons can be produced for the same mass of metal used than the Zn/air battery. Al is also lighter than Zn

(g) The white solid is aluminum hydroxide. There are insufficient hydroxide ions to dissolve the insoluble amphoteric aluminum hydroxide

(h) 19.1 g

07ZZ06-3-Q-06

(a) The plastic artifact is a non-electrical conductor. It has to be connected to the negative terminal of the battery

(b) 9.04 hr

07ZZ06-3-Q-07

(a)(i) 2H2O(l) 2e H2(g)

2OH(aq); 2Cl(aq)

Cl(g) 2e

(ii) 30.3 kg

(iii) Cl2(g) 2NaOH(aq)

NaCl (aq) NaClO(aq)

H2O(l)

(iv) OH instead of Cl will discharge at the anode to give O2 gas

(b)(i) Zn(s) Zn2(aq)

2e; 2H2O(l) O2(g)

4H(aq) 4e

(ii) 5.10 g

07ZZ06-3-Q-08

(a)(i) 63.5

(ii) 2

(iii) 31.75 g

(b)(i) Gold does not tarnish or get oxidized

in air as Ecell < 0

(ii) Yes, it would disproportionate. The reaction is feasible

(iii) Au will not be obtained as it will undergo disproportionation

07ZZ06-3-Q-09

(i) 2H2O 2e H2

2OH; Cu(s)

Cu2(aq) 2e

(ii) Cu2 formed at the

anode oxidizes I to I2,

while Cu2 reacts with

I of the electrolyte to form white precipitate CuI

7 equilibria

7 - 35

Answer keys:

MCQs 07ZZ07-1-M-01 D

07ZZ07-1-M-02 C

07ZZ07-1-M-03 C

07ZZ07-1-M-04 B

07ZZ07-1-M-05 D

07ZZ07-1-M-06 B

07ZZ07-1-M-07 D

07ZZ07-1-M-08 D

07ZZ07-1-M-09 D

07ZZ07-1-M-10 A

07ZZ07-1-M-11 D

07ZZ07-1-M-12 D

07ZZ07-1-M-13 B

07ZZ07-1-M-14 B

07ZZ07-1-M-15 D

07ZZ07-1-M-16 C

07ZZ07-1-M-17 B

07ZZ07-1-M-18 B

07ZZ07-1-M-19 D

07ZZ07-1-M-20 C

07ZZ07-1-M-21 D

07ZZ07-1-M-22 A

07ZZ07-1-M-23 D

07ZZ07-1-M-24 D

07ZZ07-1-M-25 C

07ZZ07-1-M-26 D


(a) 0.09, 0.21, 0.21

(b) 0.49 mol dm3

(c) reaction is endothermic since endothermic reactions are

favoured by increase in temperature

(d) Kc remains unchanged

(e) 98,9; 100,6; 102,1

07ZZ07-1-Q-02

(a)(i) Kc

I

I

2 2

2

H

H

(ii) 3.92 104 mol dm3

(iii) 9.08 104 mol

(b) White HI fumes will decompose to form colourless hydrogen gas and purple iodine vapour

(c) 454 kPa

07ZZ07-1-Q-03

(a)(i) Low pressure (1 atm) favours yield of product; Inert gas present allows an even lower pressure of C7H16; high temperature (300oC) is used to give a better yield of product

(ii) Suitable hydrogenating catalyst such as Ni

(b)(i) C7H16 0.0217 P atm; C7H8

0.196 P atm; H2 0.783 P atm

(ii) Kp

47 8 2

7 16

C H H

C H

P P

P

(iii) 0.737 atm

(c) 1 : 3

07ZZ07-1-Q-04

(a) Kc

2 2

2 2

SO C

SO C

l

l

(b) 5.00 mol1dm3; 8.33 mol1dm3

(c) The forward reaction is exothermic

(d) SO2 has been added

(e) Position of equilibrium shifts right to reduce number of gaseous molecules

07ZZ07-1-Q-05

(a)(i) an increase in pressure increases the percentage yield of the product, favouring the forward reaction

(ii) an increase in temperature decreases the percentage yield of the product, favouring the backward reaction

(iii) 70%

(iv) Higher pressure may increase the percentage yield of the product

(v) By removing the products once they are formed

(b) Dynamic equilibrium refers to a state in a reversible reaction in which the rates of forward and backward reactions have become equal. Catalysts do not affect the equilibrium position; instead they alter the activation energies of both forward and backward reactions to attain equilibrium more quickly

(c)(i) 43.9%

(ii) 1.84 1013 Pa2

07ZZ07-1-Q-06

(a) 3NH HC

1

P P l

atm2

(b) 0.0550 atm; 1.03 atm

(c)(i) 1.24 g

(ii) NH3 and HCl are real gases

(d) By LCP, the equilibrium position shifts right to favour endothermic reaction

07ZZ07-1-Q-07

(a)(i) Colour intensity is proportional to [NO2] in mixture

(ii) The initial slope is proportional to initial rate of reaction

(iii) The system has reached a state of dynamic equilibrium

(iv) The forward reaction is exothermic, as less NO2 is produced

(b)(i) ⅓

(ii) Kp remains unchanged

07ZZ07-1-Q-08

(a)(i) The position of equilibrium shifts left


7 - 36

(ii) The position of equilibrium shifts to the left

(b) 26.8 kPa

07ZZ07-1-Q-09

(a) 18.6 atm; 55.8 atm

(b) 4.88 103 atm2

(c)(i) Apparent molar mass decreases

(ii) Apparent molar mass increases

(d) 9.85

07ZZ07-1-Q-10

(a)(i) A 1; B 1; C 2

(ii) 4.95 106 Pa

(iii) 3.23 106 Pa1

07ZZ07-1-Q-11

(a)(i) 9

(ii) 0.259 atm

(b)(i) The enthalpy change of reaction is negative. Equilibrium shifted to the left

(ii) 5.4 102 atm2

07ZZ07-1-Q-12

(a) Kc 2

22 2

[CuL (oil)][H (aq)]

[Cu (aq)][HL(oil)]

(b) 6.25 105 mol dm3

(c) 99.9%

(d) Less copper would be extracted. Position of equilibrium shifted to the left

07ZZ07-1-Q-13

(a)(i) 82.1

(ii) 0.54

(iii) 8.35 106 N1 m2

(iv)(I) The degree of dissociation increases as equilibrium shifts to the right

(II) The degree of dissociation increases as equilibrium shifts to the right

07ZZ07-1-Q-14

(a) Le Chatelier’s principle states that if a change is made to a system in equilibrium, the system

reacts in such a way as to tend to oppose the change, and a new equilibrium is formed

(b)(i) H2O(l) H(aq) OH(aq)

(ii) alcohol carboxylic acid

ester water

(iii) 2NO2 (g) N2O4 (g) H ve

(c)(i) Kp

3 2

5

PC C

PC

P P

P

l l

l

(ii) ⅓

(iii) ⅓ atm

07ZZ07-1-Q-15

(a)(i) The equilibrium position is unaffected

(ii) The equilibrium position shifts right

(b)(i) Kp 2

2

2NO O

NO

P P

P

(ii) 3.69 104 Pa

(iii) Reduced pressure in vessel

(iv) Rate k[NO2]

(v) NO2(g) NO(g) O2(g) (slow)

07ZZ07-1-Q-16

(a)(i) Low temperature and greater air flow

(ii) Lower temperature results in a decrease in NO production. Greater air flow increases the amount of NO formed

(iii) Greater air flow decreases CO but increases amount of NO formed

(b) Mr 28.8

(c) The low value indicates that the equilibrium is very much to the left, hence reaction hardly occurs

07ZZ07-1-Q-17

(a)(i) The percentage of NH3 increases with increased pressure

(ii) The yield at 400oC is higher than that at 600oC

(b)(i) 1.35

(ii) 9.26

(iii) A buffer is a solution which resists a change in pH when small amounts of acid or base are added

(iv) NH3 H NH4; NH4

OH

NH3 H2O

07ZZ07-1-Q-18

(a)(i) Kp 2

2CO

CO

P

P

(ii) 3.06 atm

(iii)(I) The position of equilibrium shifts left

(II) The position of equilibrium shifts left

(b)(i) 1013 kJ mol1

(ii) The covalent bond in CO has ionic character while that in N2 does not

MCQs 07ZZ07-2-M-01 B

07ZZ07-2-M-02 B

07ZZ07-2-M-03 B

07ZZ07-2-M-04 D

07ZZ07-2-M-05 C

07ZZ07-2-M-06 D

07ZZ07-2-M-07 A

07ZZ07-2-M-08 B

07ZZ07-2-M-09 C

07ZZ07-2-M-10 D

07ZZ07-2-M-11 C

07ZZ07-2-M-12 D

07ZZ07-2-M-13 C

07ZZ07-2-M-14 B

07ZZ07-2-M-15 C

07ZZ07-2-M-16 A

07ZZ07-2-M-17 D

07ZZ07-2-M-18 A

07ZZ07-2-M-19 A

7 equilibria

7 - 37

07ZZ07-2-M-20 C

07ZZ07-2-M-21 B

07ZZ07-2-M-22 A

07ZZ07-2-M-23 C

07ZZ07-2-M-24 C

07ZZ07-2-M-25 B

07ZZ07-2-M-26 D

07ZZ07-2-M-27 D

07ZZ07-2-M-28 B

07ZZ07-2-M-29 C

07ZZ07-2-M-30 B

07ZZ07-2-M-31 C

07ZZ07-2-M-32 D

07ZZ07-2-M-33 C


(a)(i) Ka 2

8 4 4

8 4 4

[C H O ][H ]

[HC H O ]

(ii) 6.19

(iii) HC8H4O4 OH C8H4O4

2 H2O

(b)(i) Compounds are still reacting. Titration was carried out rapidly to minimise changes in equilibrium composition

(ii) Kc 10 9 4 2

8 4 4 2 5

[C H O ][H O]

[HC H O ][C H OH]

(iii) 0.113

(iv) Concentrated sulphuric acid removes H2O; equilibrium position shifts right

(v) 0.374 mol dm3

07ZZ07-2-Q-02

(a) N(C3H5OH)3 H

[NH(CH3H5OH)3]

(b)(i) 6.25 102 M

(ii) Since it is lower than 12.8, therefore it is a weak base

(iii) 3.98 105 M

(iv) 11.2

(c)(i) 1.8 1012 mol3 dm9

(ii) 1.8 108 M

(iii) The first sample favours good cultivation of rice crop

07ZZ07-2-Q-03

(a)(ii) the OH present makes the solution alkaline

(b) 2.67 106 g

07ZZ07-2-Q-04

(a)(i) 8.97

(ii) slight drop in pH of 0.03

(b) 2.29 108 M

07ZZ07-2-Q-05

(a)(i) Excess H ions are removed

through reaction with HCO3 to

form H2CO3

(ii) 6.40

(b)(i) 96.5 cm3

(ii) Ag2CrO4 would be precipitated

(c) pKb(BOH) > pKb(NH3), hence BOH is a weaker base than NH3

07ZZ07-2-Q-06

(a)(i) 3.64

(ii) 10.5

(b)(i) Ksp [Al3][OH]3 mol4 dm12

(ii) s

3

spw

[H ]K

K

(iii) 31.6 M

07ZZ07-2-Q-07

(a) Ka

RCOO H

RCOOH

(b) The acid strength increases from CH3COOH to ClCH2COOH to Cl2CHCOOH

(c) 3.15

(d) ClCH2COO(aq) H2O(l)

ClCH2COOH(aq) OH(aq); the equivalence point is more than 7

07ZZ07-2-Q-08

(a) 2.55

(b) 11.8

(c) 12.1

(d)(i) Yellow

(ii) No. It does not change colour at the equivalence point of the reaction which most likely falls at a pH of above 7

07ZZ07-2-Q-09

(a)(i) 6.94 105 M

(ii) An acidic buffer is set up as both HA and NaA are present

(iii) At the equivalence point, the salt produced hydrolyses to

produce OH ions

(iv) Litmus

(b)(i) 5C3H4O2 12MnO4 36H

15CO2 12Mn2 28H2O

(ii) 43.2 cm3

07ZZ07-2-Q-10

(a)(i) Ba(OH)2(aq) H2SO4(aq)

BaSO4(s) 2H2O(l)

(ii) 12.5 cm3

(iii) Before the addition of acid, the

ions present are Ba2 and OH. From 0 to v cm3 of acid added, number of free ions reduced as BaSO4 is formed. At v cm3 of acid, zero conductivity. Above v cm3,

excess acid increases H and

SO42 ions

(b)(i) pH is about 10; B4O72 H2O

HB4O7 OH

(ii) Green. A buffer solution resists changes in pH

07ZZ07-2-Q-11

(a)(i) ⅔ n

(ii) 2 : 1

(iii) 2.1 104 M

(b) The sharp change in pH for this

titration occurs from pH 7 11

(c) pH remains fairly constant when a small amount of HCl is added;

[X] [H] HX

07ZZ07-2-Q-12

(a)(i) 1.30

(ii) 12.2


7 - 38

(b) 4.10g

(c) Since HCl is a strong acid and

CH3COOH is a weak acid, [H] from HCl is greater than that from CH3COOH

07ZZ07-2-Q-13

(a)(i) 0.16

(ii) Concentration of the conjugate acid in the smoker’s urine increases

(b)(i) 4.00 106 mol3 dm9

(ii) The dissociation of calcium hydroxide is exothermic

07ZZ07-2-Q-14

(a)(i) 3.61 105 M

(ii) AgCl is precipitated out before Ag2CrO4

(b) 4.99 106 M; Potassium chromate(V) is a suitable indicator as red Ag2CrO4 only appears when negligible amount

of Cl

(c)(i) 2CrO42(aq) 2H(aq)

Cr2O72(aq) H2O(l)

(ii) 4.50 1010 mol3 dm9

07ZZ07-2-Q-15

(i) CH3(CH2)3NH2 H2O

CH3(CH2)3NH3 OH

(ii) 11.5

(iii) 0.200M

(iv) Since ionic product > Ksp of magnesium hydroxide, a precipitate of magnesium hydroxide will be formed

07ZZ07-2-Q-16

(a)(i) By LCP, more AgCl would dissolve in order to produce silver ions

(ii) 1.17 105 mol dm3

(b)(i) B H2O BH OH

(ii) 0.400 dm3 of HCl and 0.600 dm3 of B

(iii) pH 8.9

07ZZ07-2-Q-17

(a) 0.0200 M

(b) 0.100 M; 2.5 104 M

(c) 5.0 103 M

(d) The solubility of CaSO4 is decreased in the presence of Ca(OH)2 due to the common ion effect

07ZZ07-2-Q-18

(a)(i) H(aq) ClO(aq) HClO(aq);

OH(aq) HClO(aq) ClO(aq)

H2O(l)

(ii) 4.7

(b)(i) Chloric(I) acid is very corrosive, hence it is safer to add indirectly in solid tablet form

(ii) HClO

(iii) 7.4

(iv) NH3(aq) HClO(aq) NH2Cl(aq)

H2O(l)

07ZZ07-2-Q-19

(a) 2.65

(b) 2.35g

(c)(i) Ca(OH)2

(ii) Phenolphthalein would be a suitable indicator as it changes colour at high pH values

(iii) C16H17O9 undergoes salt

hydrolysis

(iv) 13.3

07ZZ07-2-Q-20

(a) 11.8

(b) 10.5

(c) 5.91

07ZZ07-2-Q-21

(a)(i) PH bond is non-polar. The

OH bonds are polar, thus these two H atoms are acidic

(ii) HPO32 is a stronger base since

(iii) 50.0 cm3

(iv) The graph must have two inflexions with the pKa values and the end-point volumes labelled

(b) 9.7 104 M; 6.5 104 M; 3.3

104 M

07ZZ07-2-Q-22

(a) pKa log10 Ka

(b) H3BO3 H2BO3 H

(c) 5.12

(d)(i) 40 cm3

(ii) Phenolphthalein

07ZZ07-2-Q-23

(a)(i) Ksp [Mg2][F]2

(ii) 2.10 103 mol dm3

(iii) MgF2 is a suitable source of fluoride ions

(iv) 7.4 104 mol dm3

(b)(i) An orange / reddish brown colour is produced

(ii) MgBr2 Cl2 MgCl2 Br2

07ZZ07-2-Q-24

(a) An acid is a substance which can donate a proton to a base

(b)(i) A weak acid does not fully

dissociate in water; RCOOH

RCOO H

(c)(i) A buffer is a solution which resists changes in pH on addition of small amounts of an acid or base

(ii) C8H7O2CO2 Na C8H7O2CO2

Na; C8H7O2COOH

C8H7O2CO2 H

07ZZ07-2-Q-25

(a)(i) The conjugate acid of the weak base, undergoes hydrolysis to

give NH3 and H3O, hence pH < 7

(ii) 5.15

(b) Cream precipitate of AgBr is formed

07ZZ07-2-Q-26

(a) Buffer solution is a solution that can resist pH change when small amounts of acid or base are added to it

7 equilibria

7 - 39

(b) Ka

3

2 3

HCO H

H CO

(c) 19.8

(d) H HCO3 H2CO3

(e) As [CO2 (aq)] increases, the position of equilibrium shifts right as more CO2 (aq) is exhaled through the lungs as CO2 (g). This leads to a higher rate of breathing

(f)(i) Ksp [Ca2][CO32]

(ii) 8.70 109 mol2 dm6

07ZZ07-2-Q-27

(a)(i) 1.38 105; 1.44 105; 1.80

1010; 1.80 1010

(ii) 1.80 109 mol dm3

(b) Solubility would decrease due to the presence of carbonate ions in sea water (common ion effect)

07ZZ07-2-Q-28

(a)(i) The graph has one inflexion point

(ii) CH3CH(OH)CO2 H2O

CH3CH(OH)CO2H OH

(iii) 0.0316 mol dm3

(iv) 1.26 104 mol dm3

(b)(i) 0.0159 mol dm3

(ii) 1.61 105 mol3 dm9

(iii) Solubility of lead (II) chloride decreases due to the common ion effect

07ZZ07-2-Q-29

(a)(i) N2H4 H2O N2H5 OH;

N2H5 H2O N2H6

2 OH

(ii) Kb2 is much smaller than Kb1 due

to repulsion when N2H5 gains

H

(b)(i) 10.5

(ii) 7.93

(iii) 4.55

8 reaction kinetics

8 - 21

Answer keys:

MCQs 07ZZ08-1-M-01 A

07ZZ08-1-M-02 C

07ZZ08-1-M-03 B

07ZZ08-1-M-04 C

07ZZ08-1-M-05 B

07ZZ08-1-M-06 B

07ZZ08-1-M-07 B

07ZZ08-1-M-08 A

07ZZ08-1-M-09 A

07ZZ08-1-M-10 B

07ZZ08-1-M-11 D

07ZZ08-1-M-12 B

07ZZ08-1-M-13 A

07ZZ08-1-M-14 C

07ZZ08-1-M-15 D

07ZZ08-1-M-16 D

07ZZ08-1-M-17 B

07ZZ08-1-M-18 B

07ZZ08-1-M-19 D

07ZZ08-1-M-20 A

07ZZ08-1-M-21 C

07ZZ08-1-M-22 D

07ZZ08-1-M-23 C

07ZZ08-1-M-24 D

07ZZ08-1-M-25 D

07ZZ08-1-M-26 A

07ZZ08-1-M-27 B

07ZZ08-1-M-28 B

07ZZ08-1-M-29 D


(a)(i) Quench solution mixture and titrate remaining I2 against

standard solution of sodium thiosulphate

(ii) propanone 1; acid 1; iodine 0

(iii) Rate k[CH3COCH3][H]

(b) Stage 1 is rate determining step; step 2 is fast step

(c) At higher temperature, there are more molecules which possess energy equal or greater than the activation energy

07ZZ08-1-Q-02

(a)(i) 2; 1

(ii) Rate k[NO]2[H2]

(b) 5000 mol2 dm6 min1

(c) 0.0050 M

(d) Step II

(i) Rate k1 [NO]2[H2]

(ii) Equations I, II and III add up to the overall equation

07ZZ08-1-Q-03

(i) 38, 6, 18, 15, 2, 19

(ii) Constant half-life graph confirms that the decomposition of ozone is first-order

(iii) Rate k[O3]

(iv) O3 O O2; O3 O 2O2

07ZZ08-1-Q-04

(a)(i) rate k[I(aq)][ S2O82(aq)]; k

2.05 103 mol1 dm3 s1

(ii) Fe2 behaves as a homogeneous catalyst

(iii) Titrimetric method

(b)(i) 2.05 104 s

(ii) 6.15 104 s

07ZZ08-1-Q-05

(a)(i) Reaction is first order with respect to KI; reaction is first order with respect to K2S2O8

(ii) Rate k [KI] [K2S2O8]; 0.0281

mol1 dm3 min1

(b) Colorimetry method

07ZZ08-1-Q-06

(a) Order of reaction is the sum of the orders of reaction with respect to the reactants

(b)(i) first; zero; first

(ii) Rate k [(CH3)2CO][CN]

(iii) Mechanism B, step 1

(iv) The base acts as a catalyst. It provides an alternative pathway which has lower activation energy

07ZZ08-1-Q-07

(a) To determine the amount of iodine present at the time of titration

(b) Vn Vt is directly proportional to the concentration of iodine ions remaining in the reaction mixture

(c) Order of reaction with respect to

iodide 1

(d)(i) Rate k[I][S2O82]

(ii) half-life is doubled

(e) When temperature is increased, there is an increase in the average kinetic energy of the reactants. The increase in the number of effective collisions leads to an increase in reaction rate

07ZZ08-1-Q-08

(a) A straight line graph is obtained. Order of reaction with respect to the concentration of hydrogen is 1

(b) Repeat experiment keeping [H2] constant while varying [NO]

(c) Rate k[NO]2[H2]

(d) Mechanism A

(e)(i) 8r

(ii) r

07ZZ08-1-Q-09

(a) Vf Vt is proportional to [N2O5] remaining in the reaction mixture

(b) The half-life is approximately constant at 23 min


8 - 22

(c) 0.0301 min1

(d) There is an increase in the frequency of effective collisions, leading to an increase in the rate of reaction

07ZZ08-1-Q-10

(a) Both catalyst and reactants are in same physical state; variable oxidation states

(b)(i) Repulsion between similarly-charged reactants

(ii) S2O82(aq) 2Fe2(aq)

2SO42(aq) 2Fe3(aq)

2I(aq) 2Fe3(aq) I2(aq)

2Fe2(aq)

(c) MnO2 is acting as a heterogeneous catalyst

07ZZ08-1-Q-11

(a)(i) 7.4; 5.0; 3.4; 2.4

(ii) Constant half-life of 1900s

(b) 4 104 s1

(c) Increasing reaction rate

(d) 4.6 Pa

(e) 324 kJ mol1

07ZZ08-1-Q-12

(a) Rate k[NO2]2; 0.090 mol1 dm3

s1

(b) Mechanism II

(c)(i) Step 1

(ii) Step 2

07ZZ08-1-Q-13

(a) 70 min

(b) 0.0198 min1

07ZZ08-1-Q-14

(a)(i) first order; first order

(ii) OH is an inhibitor

(iii) Rate k[OCl][I][OH]1

07ZZ08-1-Q-15

(a) Potassium peroxodisulphate was used in large excess so that

[S2O82(aq)] remains

approximately constant

(b) 20.0 cm3

(c) t ½ 5 min (constant)

(d) Repeat experiment but using aqueous sodium peroxodisulphate of

concentration 4.00 mol dm3

(e) 0.1386 mol1 dm3 min1

07ZZ08-1-Q-16

(a) Constant half-life at 5 min

(b) first order

(c) 9.24 102 mol1 dm3 min1

(d) When temperature is increased, there is an increase in the average kinetic energy of the reactants. Therefore there is an increase in the frequency of effective collisions, leading to an increase in the rate of reaction

07ZZ08-1-Q-17

(a) Since half-life is constant, order of reaction with respect to N2O is 1

(b) Rate k[NO]; 2.15 104 s1

(c) 9675s

(d) Gold acts as a catalyst

07ZZ08-1-Q-18

(a) 0.00; 0.67; 1.41; 2.40; 3.63; 4.63

(b) constant half-life; 0.169 h1

(c) 9.26 atm

(d)(i) The initial rate doubles with no change in half-life

(ii) The initial rate halves with no change in half-life

07ZZ08-1-Q-19

(a) Rate k [I3][S2O3

2]

(b) 1.5 105 mol1 dm3 s1

(c) Rate k’[I2][S2O32] where k’

kK’c

07ZZ08-1-Q-20

(a) 2N2O5 4NO2 O2

(c)(i) Reaction is first order with respect to N2O

(ii) 0.0315 min1

(d) Rate k[N2O5]

(e) [N2O5] is doubled, hence rate is also doubled

(f)(i) Shape of the NO2 ion is linear

07ZZ08-1-Q-21

(a) Decreasing curve with at least one half-life shown

(b) rate k[paracetamol]

(c) 0.257 h1

(d) 5.4 h

(e)(i) Curve must show faster reaction with shorter half-life

(ii) pH of body fluid

07ZZ08-1-Q-22

(a) Since successive half-lives are approximately constant, the reaction is first order with respect to H2O2

(b) 0.0667 mol dm3

(c) Rate k[H2O2]; 0.0139 s1

07ZZ08-1-Q-23

(a) Increasing number of effective collisions leading to an increase in rate for a reaction at higher temperature

(b) [H2O2] / mol dm3; [H] / mol

dm3

(c)(i) 25.0 cm3

(ii) There is a large excess of H2O2

(iii) Constant half-life for plot which is a smooth curve

07ZZ08-1-Q-24

(a) PCH4 4no. of mole of CH

total no. of moles Ptotal

(b) Graph is a smooth curve with a constant half-life, thus the reaction is of the first order

(c) 130 mm Hg

(d) 4.6 103 s1

(e) The aqueous reaction is not dependent on pressure changes, whereas for gaseous reactions, the frequency of collisions between particles increases with pressure


9 - 62

Answer keys:

MCQs 07ZZ09-1-M-01 C

07ZZ09-1-M-02 B

07ZZ09-1-M-03 B

07ZZ09-1-M-04 B

07ZZ09-1-M-05 D

07ZZ09-1-M-06 D

07ZZ09-1-M-07 B

07ZZ09-1-M-08 B

07ZZ09-1-M-09 B

07ZZ09-1-M-10 B

07ZZ09-1-M-11 D

07ZZ09-1-M-12 B

07ZZ09-1-M-13 D

07ZZ09-1-M-14 B

07ZZ09-1-M-15 D

07ZZ09-1-M-16 A

07ZZ09-1-M-17 A

07ZZ09-1-M-18 D

07ZZ09-1-M-19 D

07ZZ09-1-M-20 A

07ZZ09-1-M-21 A

07ZZ09-1-M-22 A

07ZZ09-1-M-23 C

07ZZ09-1-M-24 B

07ZZ09-1-M-25 A

07ZZ09-1-M-26 B

07ZZ09-1-M-27 C

07ZZ09-1-M-28 A

07ZZ09-1-M-29 B

07ZZ09-1-M-30 C

07ZZ09-1-M-31 B

07ZZ09-1-M-32 C

07ZZ09-1-M-33 D

07ZZ09-1-M-34 D

07ZZ09-1-M-35 A

07ZZ09-1-M-36 A

07ZZ09-1-M-37 D

07ZZ09-1-M-38 A

07ZZ09-1-M-39 A

07ZZ09-1-M-40 D

07ZZ09-1-M-41 D

07ZZ09-1-M-42 A

07ZZ09-1-M-43 D

07ZZ09-1-M-44 A

07ZZ09-1-M-45 D

07ZZ09-1-M-46 D

07ZZ09-1-M-47 C


(a)(i) MgSiO3(s) MgO(s)

SiO2(s)

(ii) MgO, Al2O3, SiO2, SO2

(iii) Use concentrated

NaOH; SiO2 2OH

SiO32 H2O; SO2

2OH SO32 H2O

(b)(i) MgO and SiO2 are solids at room temperature. MgO has a giant ionic lattice structure. SiO2 has a giant macromolecular structure with strong covalent bonds. SO2 exists as a gas and is a simple covalent molecule

(ii) Bent shape

07ZZ09-1-Q-02

(a) Al. Al2O3 6H 2Al3

3H2O; Al2O3 2OH

3H2O 2Al(OH)4

(b) Si. SiO2 2OH

SiO32 H2O

07ZZ09-1-Q-03

(a) Na2O and MgO are basic oxides which have giant ionic structures consisting of oppositely charged ions

Al2O3 is an amphoteric oxide with giant ionic structure consisting of oppositely charged ions

SiO2 is an acidic oxide with a giant molecular structure consisting of atoms held together by strong covalent bonds

P4O10 and SO3 are acidic oxides with simple molecular structures consisting of discrete molecules held together by weak van der Waals’ forces

(b)(i) Si2OCl6

(ii) Si2OCl6 3H2O 2SiO2

6HCl

07ZZ09-1-Q-04

(a) Na, Mg, Al: giant metallic structure; Si: giant molecular structure; P, S, Cl, Ar: simple molecular structure

(b) NaCl aq Na Cl

MgCl2 aq Mg2

2Cl

AlCl3 6H2O

Al(H2O)63 3Cl

Al(H2O)63 H2O

Al(OH)(H2O)52 H3O

SiCl4 4H2O Si(OH)4

4HCl

PCl5 4H2O H3PO4 5HCl

(c) MgCl2 is able to conduct electricity; PCl5 is unable to conduct electricity

07ZZ09-1-Q-05

(a) Na, Mg and Al are giant metallic structures; Si has a giant covalent structure; P, S, Cl and Ar are simple molecular structures; Melting point pattern: S8 > P4 > Cl2 > Ar

(b) MgO is a basic oxide;

MgO 2H Mg2 H2O

Al2O3 is an amphoteric

oxide; Al2O3 6H

2Al3 3H2O; Al2O3

2OH 3H2O

2Al(OH)4

SO3 is an acidic oxide;

SO3 2OH SO42

H2O

c) Effective nuclear charge only increases very slightly

07ZZ09-1-Q-06

(a)(i) Na to Al: giant metallic structure – high bp; Si: giant molecular structure – high bp; P, S, Cl: lower bp - simple molecular

(ii) Na and Mg form basic

ionic oxides; MgO

2H Mg2 H2O

Al oxide is amphoteric as it is ionic with covalent character;

Al2O3 6H 2Al3

3H2O; Al2O3 2OH

3H2O 2Al(OH)4

Si, P, S and Cl form acidic covalent oxides;

P4O10 12OH

4PO43 6H2O

(b) NaCl: 7; MgCl2: 6.5; AlCl3: 4; SiCl4: 3.5

07ZZ09-1-Q-07

(a) P exists as a simple molecular structure and is considered a

9 inorganic chemistry

9 - 63

non-metal. Its chlorides are covalent compounds which also have simple molecular

structures; PCl5 4H2O

H3PO4 5HCl

(b)(i) It reacts with both acids and alkalis to form salt and water

(ii) Al2(SO4)3 3CaO

3H2O 2Al(OH)3 3CaSO4

(iii) CaO will speed up the above reaction, thus leading to the formation of more Al(OH)3. Aluminium compounds are associated with neurological damage characteristic of Alzheimer's Disease

(c)(i) Second ionization energy increases from silicon to argon across the period

(ii) For Cl, it is easier to remove one of the shared pair in 3p. For both S and P, the electron removed is unpaired

07ZZ09-1-Q-08

(a)(i) Al3 has a high

charge density

(ii) Al(OH)3 and BaSO4

(iii) Presence of soluble Ba(OH)2

(iv) Al(OH)3 OH

Al(OH)4

(b) Aluminium in wrapping food reacts with acids/alkalis in food to form soluble ions

(c)(i) Alkaline

(ii) 20.0 %

07ZZ09-1-Q-09

(a)(i) Mg has stronger metallic bonding

(ii) The variation in mp is in same order as size of the molecules

(b) P, S and Cl can expand their octet, hence the variation in oxidation number

07ZZ09-1-Q-10

(a) Both silicon dioxide and aluminium oxide are insoluble in water

(b) NaCl is held by strong ionic bonds in a giant crystal lattice structure; PCl3 is a simple and discrete covalent molecule held by weak van der Waals’ forces

(c) Ca2 has more protons

than Cl hence stronger electrostatic attraction

07ZZ09-1-Q-11

(a)(i) Highly charged Al3

polarizes the water molecules to liberate hydrogen ions. CO2 gas is produced when Na2CO3 is added;

Na2CO3 2H 2Na

H2O CO2

(ii) SiCl4 undergoes complete hydrolysis in water; CCl4 is unable to dissolve in water which is a polar solvent

(b) Sodium and magnesium oxide contain ionic bonds. Aluminium oxide is ionic with partial covalent character. Silicon, phosphorous and sulphur oxides have covalent bonding. Sodium and magnesium oxide are basic in nature; aluminium oxide is

amphoteric, while the rest are acidic

07ZZ09-1-Q-12

(a)(i) Heat dolomite to a temperature above the decomposition temperature of MgCO3 and below that of CaCO3

(ii) High melting point; used as refractory material in furnaces

(b) A is Na as its compounds have high melting points. Its oxide and chloride are ionic solids. B is P as:

PCl5 4H2O H3PO4

5HCl; C is Si as it is insoluble in water

07ZZ09-1-Q-13

(a)(i) Al2O3 2OH 3H2O

2Al(OH)4; SO2

2OH SO32 H2O

(ii) Na2O 2H 2Na

H2O; Al2O3 6H

2Al3 3H2O

(b) Al2O is ionic with covalent character

07ZZ09-1-Q-14

(a)(i) Na to Al: They are giant metallic structures

(ii) P4 to Cl2: They have simple molecular structures

(b)(i) NO2 and O2

(ii) Ba(NO3)2 and MgO

(iii) W to X: Volume increases quickly due to thermal decomposition of Mg(NO3)2; X to Y: Volume increases due to increase in temperature of gases; Y to Z: Volume increases quickly again due to thermal

decomposition of Ba(NO3)2

(iv) Volume of gas evolved by strontium nitrate will be lower at point X

07ZZ09-1-Q-15

(a) Na2O, MgO, SiO2, SO3

(b) Na2O dissolves readily in water to form an alkaline solution; MgO dissolves slightly in water to form a weakly alkaline solution; SiO2 does not dissolve in water. SO3 dissolves readily in water to form an acidic solution

(c) SiO2 has a high melting point due to its giant covalent structure. SO3 has a low melting point as it exists as simple molecules

(d) Al2O3 2OH 3H2O

2Al(OH)4; Al2O3

6H 2Al3 3H2O

07ZZ09-1-Q-16

(a) Melting point increases from Na to Al as the strength of the metallic bond increases; Si has a very high melting point due to its giant covalent structure; P, S, Cl and Ar have lower melting points since they are simple molecules

(b)(ii) NaCl(s) Na(aq)

Cl(aq) (pH 7); PCl5

4H2O H3PO4 5HCl

(pH 2)

07ZZ09-1-Q-17

(a)(i) NaCl has a giant ionic structure with strong ionic bonding, hence a high mp. AlCl3 and PCl3 have simple molecular structures, hence low mp


9 - 64

(ii) NaCl dissolves in water to give a neutral solution. AlCl3 dissolves in water to give acidic solution

Al(H2O)63 H2O

Al(OH)(H2O)52 H3O.

PCl3 undergoes hydrolysis to give

strong acids PCl3

3H2O H3PO3 3HCl

(b)(i) Soluble in polar solvents

(ii) Al tends to lose its valence electrons to F forming ions

07ZZ09-1-Q-18

(a)(i) NaCl, MgCl2, AlCl3, SiCl4 and PCl5

(ii) NaCl dissolves in water without any reaction

NaCl(aq) Na Cl (pH 7); SiCl4 is a covalent compound. It hydrolyses in water to form an acidic solution

SiCl4 4H2O Si(OH)4

4HCl (pH 12)

(b) 2S2Cl2 3H2O 3S

H2SO3 4HCl

07ZZ09-1-Q-19

(a)(i) QClm has a higher boiling and melting point than RCln. QClm is soluble in water but insoluble in benzene. RCln is soluble in benzene but insoluble in water. RCln has lower melting and boiling point than QClm

(ii) 1st IE of R is less exothermic than Q

(b) X is Mg and Y is Ba

07ZZ09-1-Q-20

Sc to V have stronger metallic bonds. Mn and Zn form weak metallic bonds.


07ZZ09-2-M-02 A

07ZZ09-2-M-03 C

07ZZ09-2-M-04 A

07ZZ09-2-M-05 B

07ZZ09-2-M-06 B

07ZZ09-2-M-07 A

07ZZ09-2-M-08 A

07ZZ09-2-M-09 A

07ZZ09-2-M-10 B

07ZZ09-2-M-11 C

07ZZ09-2-M-12 D

07ZZ09-2-M-13 D

07ZZ09-2-M-14 A

07ZZ09-2-M-15 D

07ZZ09-2-M-16 B

07ZZ09-2-M-17 C

07ZZ09-2-M-18 D

07ZZ09-2-M-19 B

07ZZ09-2-M-20 D

07ZZ09-2-M-21 B

07ZZ09-2-M-22 C

07ZZ09-2-M-23 D

07ZZ09-2-M-24 A

07ZZ09-2-M-25 B

07ZZ09-2-M-26 D

07ZZ09-2-M-27 C

07ZZ09-2-M-28 D

07ZZ09-2-M-29 D


(a)(ii) 517 kJ mol1

(b) H2 would be more

exothermic.

(c)(i) Mg is a weaker reducing agent than barium

07ZZ09-2-Q-02

(ii) Polarizing power of the cations decrease down the group

(iii) Barium hydroxide is the alkaline solution while the effervescence is due to the oxygen gas evolved

07ZZ09-2-Q-03

(a) Down Group II, cation radius increases, charge density decreases. Down

Group VII, HX bond energy decreases

(b) X Mg; Y Ca

07ZZ09-2-Q-04

(a)(i) 2Mg(NO3)2(s)

2MgO(s) 4NO2(g) O2(g)

(ii) Mg(NO3)2 will decompose at a lower temperature. Cationic size of the magnesium ion is smaller than that of barium

(b)(i) Ba2(aq) SO42(aq)

BaSO4

(ii) Hsol of BaSO4 is less

exothermic than that of MgSO4, thus less soluble

(c) n 8; Ar of M 87.2

07ZZ09-2-Q-05

MgCO3 will decompose

first; MgCO3 MgO CO2

07ZZ09-2-Q-06

(a) Lead(II) carbonate, zinc carbonate and calcium carbonate

(b)(i) The SO2 gas evolved will react with H2O to form sulphurous acid;

SO2 H2O H2SO3

(ii) the effervescence will be observed for a longer period of time

(c)(i) By increasing the amount of Mg ions, the position of equilibrium of the reaction is pushed to the left. Hence the solubility product is lowered

(ii) MgO is a principal ingredient in construction materials used for fireproofing. It has a high mp

07ZZ09-2-Q-07

(a)(i) Mg amide is less stable thermally as compared to Ba amide. The Mg ion is smaller in size as compared to the Ba ion

(ii) Similar to that of Mg amide. This is due to the similar charge

densities of Li and

Mg2 ions

(b)(i) The Hhyd becomes less exothermic down the group since the cationic size increases and charge density decreases

(ii) 2.37 102 ppm

07ZZ09-2-Q-08

(a)(i) White residue of MgO remains and pungent brown gas (nitrogen gas) evolved


9 - 65

(ii) White solid of calcium oxide crumples to form white solid which dissolves in excess water to form colourless solution of calcium hydroxide

(b)(i) BaSO4

(ii) BaO(s) ½O2(g)

BaO2(s)

(iii) 0.199g

(iv) magnesium peroxide is not stable

07ZZ09-2-Q-09

(a)(i) CaSO4 18 kJ

mol1; SrSO4 2 kJ

mol1

(ii) the solubility is

dependent on Hhyd which become less exothermic from the small Mg ion to the much larger Sr ion

(b) M(NO3)2 MO

2NO2 ½O2 where M is group II metal

(c) The peroxide ion is more polarisable than the monoxide ion

07ZZ09-2-Q-10

(a)(i) the charge density decreases down the group

(ii) Enthalpy of solution becomes more endothermic down the group

(b)(i) NH3

(ii) The blue solution contains copper (II) ions. When ammonia is added drop wise, copper(II) hydroxide (blue precipitate) and magnesium hydroxide (white precipitate) are formed. When excess ammonia is added, a complex of

[Cu(NH3)4]2, a dark blue solution is formed

(iii) All the precipitate dissolves. No residue is obtained

07ZZ09-2-Q-11

(a) A is barium; B is magnesium

(b) Sodium oxide: ionic bonding. Dissolves readily to give an

alkaline solution. pH

12 14; Aluminium oxide: ionic with partial covalent character. Insoluble in

water. pH 7; Sulphur dioxide: covalent bonding. Dissolves in water to form

sulphurous acid. pH

1 3

07ZZ09-2-Q-12

(a) The hydroxide anion is smaller than the carbonate anion and hence is less polarisable by the beryllium cation

(b)(i) the lattice energy of magnesium carbonate is higher than that of barium carbonate

(ii) the value of the lattice energy of magnesium carbonate is smaller than that of the residue (MgO)

(c)(i) 3Ba(NH2)2 Ba3N2 4NH3

(ii) 11.4 dm3

07ZZ09-2-Q-13

(a)(i) 2Mg(IO3)2 2MgO

5O2 2I2

(ii) Magnesium iodate. The magnesium ion has a smaller ionic radius, higher charge

density, larger polarizing power

(b)(i) Lattice energy of magnesium iodate is greater than that of barium iodate

(ii) Lattice energy of magnesium oxide is greater than that of magnesium iodate

(c)(i) 3I2 6OH 5I

IO3 3H2O

(ii) 0.0167 mol dm3

07ZZ09-2-Q-14

(a) CaCO3 CaO CO2;

CaO H2O Ca(OH)2

(b)(i) to neutralize acidic soils

(ii) Liberation of NH3 gas leads to loss of fertilizers added

(c) The size of the cations increases down the group, leading to the decreasing charge density of the cations and the decreasing polarizing power of the cations

(d) CaMg(CO3)2 4HCl

CaCl2 MgCl2 2CO2 2H2O; 94.3%

07ZZ09-2-Q-15

(i) Decreases down the

group; M(OH)2 MO

H2O; M(NO3)2 MO

2NO2 ½O2

(ii) The size of the cations increases down the group, leading to the decreasing charge density and polarizing power of the cations

07ZZ09-2-Q-16

(a) The mp of the group II elements decreases down the group; the mp of the group VII

elements increases down the group

(b) calcium carbonate is thermally less stable than strontium

carbonate; SrCO3

SrO CO2

(c) 12.2%

07ZZ09-2-Q-17

(a)(ii) magnesium carbonate is less stable and decomposes at a lower temperature

(b)(i) Mg(OH)2 precipitates out as a white precipitate

(ii) NH4 lowers [OH] and

hence Mg(OH)2 dissolves


07ZZ09-3-M-02 D

07ZZ09-3-M-03 D

07ZZ09-3-M-04 C

07ZZ09-3-M-05 A

07ZZ09-3-M-06 C

07ZZ09-3-M-07 B

07ZZ09-3-M-08 A

07ZZ09-3-M-09 C

07ZZ09-3-M-10 C

07ZZ09-3-M-11 D

07ZZ09-3-M-12 C

07ZZ09-3-M-13 A

07ZZ09-3-M-14 D

07ZZ09-3-M-15 B

07ZZ09-3-M-16 B

07ZZ09-3-M-17 A

07ZZ09-3-M-18 B


9 - 66

07ZZ09-3-M-19 D

07ZZ09-3-M-20 D

07ZZ09-3-M-21 C

07ZZ09-3-M-22 C

07ZZ09-3-M-23 B

07ZZ09-3-M-24 A

07ZZ09-3-M-25 A

07ZZ09-3-M-26 A

07ZZ09-3-M-27 A

07ZZ09-3-M-28 D

07ZZ09-3-M-29 C

07ZZ09-3-M-30 B

07ZZ09-3-M-31 A

07ZZ09-3-M-32 C

07ZZ09-3-M-33 B

07ZZ09-3-M-34 D

07ZZ09-3-M-35 C


(a) Chlorine is a gas, bromine is a liquid iodine is a solid

(b)(i) ClO: 1; ClO3: 5

(ii) Cl2 2OH Cl

ClO H2O; 3Cl2

6OH 5Cl ClO3

3H2O

07ZZ09-3-Q-02

(a) Cl2 is a stronger oxidizing agent

(b)(i) cold: 2NaOH Cl2

NaCl NaOCl

H2O; hot: 3Cl2

6NaOH 5NaCl

NaClO3 3H2O

(ii) NaOCl and NaClO3 can easily decompose in light to give oxygen

(c)(ii) chlorine dioxide is able to undergo

hydrogen bonding with water

(iii) AgCl; O2; 2AgClO3 Cl2

2AgCl O2 2ClO2

07ZZ09-3-Q-03

(a) Bromine oxidizes the iodide to iodine but not the chloride

(b) ClO2 undergoes disproportionation as it is reduced and oxidized at the same time

(c)(i) Astatine oxidizes thiosulphate to tetrathionate

(ii) HAt immediately further reacts with conc. H2SO4 to give At2

(d) Add aqueous AgNO3 to form 2 precipitates. Add aqueous NH3. AgCl dissolves while AgI remains as precipitate

07ZZ09-3-Q-04

(a) Brown solution is I3

while the black crystals are I2

(b) For NaCl, misty fumes of HCl are produced; for KI, purple fumes are produced

07ZZ09-3-Q-05

(a)(i) reaction with chlorine is rapid, with bromine is slow, and none with iodine

(ii) Cl2 and Br2, oxidize thiosulphate to sulphate. None with iodine

(b)(i) 3Cl2(g) 6NaOH(aq)

5NaCl(aq)

NaClO3(aq) 3H2O(l)

(ii) 16700 dm3

07ZZ09-3-Q-06

(a) 3Cl2 6NaOH 5NaCl

NaClO3 3H2O

(b)(i) Br2; 2HBr H2SO4

Br2 SO2 2H2O

(ii) H2S

07ZZ09-3-Q-07

(a) oxidation is almost impossible for fluoride due to its very positive redox potential

(b)(i) Cl - white fumes of hydrogen chloride gas are produced; Br - white fumes of hydrogen bromide gas are produced. On warming, the reddish-brown gas of bromine can be observed; I - violet vapour of iodine gas will be observed. There will be more violet vapour on warming and a little hydrogen iodide gas

(ii) Cl - explosive in sunlight but slow in the dark; Br - requires heating and a platinum catalyst; I - slow even on heating with a platinum catalyst

(c)(i) x 2 and y 1

(ii) Cs

07ZZ09-3-Q-08

(a) Thermal stability decreases down the group

(b) 5H2O S2O32 4X2

10H 8X 2SO42

(c)(i) Y2 2S2O32 2Y

S4O62

(ii) X is a stronger oxidizing agent than Y

(iii) X2 is chlorine or bromine. Y2 is iodine

07ZZ09-3-Q-09

(a)(i) NaI(s) H2SO4(l)

NaHSO4(s) HI(g);

2NaI(s) 3H2SO4(l)

SO2(g) I2(l)

2NaHSO4(s) 2H2O(l)

(ii) HI cannot reduce phosphoric(V) acid

(b)(i) Passing chlorine into hot sodium hydroxide solution

(ii) Decomposed to give oxygen gas

07ZZ09-3-Q-10

(a)(i) Si2OBr6

(ii) The cream precipitate is silver bromide. Cyanide anions form more stable complexes with silver than ammonia

(b) Thermal stability decreases down the group

(c)(i) redox reaction

(ii) 3Br2(g) 6KOH(aq)

5KBr(aq) KBrO3(aq) 3H2O(l)

07ZZ09-3-Q-11

(a)(i) chlorine gas

(ii) Cl2 H2O 2H ClO

Cl

(iii) I reacts with conc H2SO4 to give the diatomic gas

(iv) Hydrogen astatide would be a more acidic solution than hydrogen chloride

(b) 3.00 mol dm3

07ZZ09-3-Q-12

Grid 1 - The size of the

M2 ion increases down the group

Grid 2 - Electronegativity and ionization energy


9 - 67

decreases down the group

Grid 3 - The halogen atom increases in size down the group

Grid 4 - The molecular size increases down the group

07ZZ09-3-Q-13

(a)(i) Sn 2I2 SnI4

(ii) The purple colour of iodine is discharged

(iii) filtered to remove unreacted tin

(iv) covalent

(v) 0.015

(b)(i) A reddish orange colour is discharged

(ii) Purple fumes produced with HI but no observation with HCl

07ZZ09-3-Q-14

(a) NaF H2SO4 HF

NaHSO4; NaCl H2SO4

HCl NaHSO4

(b) HBr and HI are further oxidised to bromine and iodine

(c) H2 Br2 2HBr; 2NaI

H3PO4 2HI NaHPO4

(d) HF has higher mp due to stronger hydrogen bonding. In aqueous solution, HF is a weaker acid due to higher bond energy of

HF bond

07ZZ09-3-Q-15

(a)(i) Br ; I

(ii) 0.144g

(iii) 55.96%

(b)(i) 2Cl(aq) Cl2(g)

2e; 2H2O(l) 2e

H2(g) 2OH(aq)

(ii) Chlorine oxidizes and kills bacteria in water

07ZZ09-3-Q-16

(a) Down the group, volatility of the group VII elements decreases

(b)(i) 2HIO3 I2O5 H2O

(ii) 43.8 %

07ZZ09-3-Q-17

(a)(i) the hydrogen halides decompose more readily upon heating

(ii) the reducing power of the halide ions increases down the group

(b)(i) 0.002

(ii) 3

(iii) 3Cl2 I2 2ICl3

(c) Polyvinyl chloride is used as an insulator and in pipes

07ZZ09-3-Q-18

(a) thermal stability is in the order HCl > HBr > HI

(b)(i) 2NaBr(s) 2H2SO4(l)

Br2(l) SO2(g)

2H2O(l) Na2SO4(aq)

(ii) 0.630 mol dm3

07ZZ09-3-Q-19

(a)(i) First ionisation energy is the energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of positive ions

(ii) first ionisation energy decreases down the group

(b)(ii) thermal stability decreases

(iii) HI is easily oxidized to iodine

07ZZ09-3-Q-20

(a)(i) A is HBr; B is Br2. C is HCl; D is HI; E is I2. F is Br ion

(ii) reducing power of the halide ions increases

from Cl to Br to I

(iii) Chlorine gas; Manganese (IV) oxide acts as oxidising agent

07ZZ09-3-Q-21

(a)(i) Violet organic layer shows that the iodine formed is dissolved in tetrachloromethane. Chlorine is a stronger oxidizing agent than iodine

(ii) Cold NaOH - 2OH Cl2

ClO Cl 2H2O;

Hot NaOH - 6OH

3Cl2 ClO3 5Cl

3H2O

(b)(i) HI which can be oxidized by concentrated sulphuric acid to form iodine

(ii) H2 I2 2HI;

Reagents: hydrogen gas and iodine gas; Conditions: 400oC, platinum catalyst

07ZZ09-3-Q-22

(a) Chlorine is a stronger oxidising agent than iodine

(b) White precipitate of AgCl and yellow precipitate of AgI will be formed. In excess NH3, AgCl dissolves

(c)(i) Br

(ii) 2H BrOx 2I I2

Br

(iii) x 1


07ZZ09-4-M-02 B

07ZZ09-4-M-03 A

07ZZ09-4-M-04 C

07ZZ09-4-M-05 C

07ZZ09-4-M-06 A

07ZZ09-4-M-07 A

07ZZ09-4-M-08 B

07ZZ09-4-M-09 D

07ZZ09-4-M-10 D

07ZZ09-4-M-11 C

07ZZ09-4-M-12 D

07ZZ09-4-M-13 D

07ZZ09-4-M-14 A

07ZZ09-4-M-15 A

07ZZ09-4-M-16 D

07ZZ09-4-M-17 B

07ZZ09-4-M-18 B

07ZZ09-4-M-19 A

07ZZ09-4-M-20 D

07ZZ09-4-M-21 A

07ZZ09-4-M-22 C

07ZZ09-4-M-23 C

07ZZ09-4-M-24 B

07ZZ09-4-M-25 B

07ZZ09-4-M-26 C

07ZZ09-4-M-27 D

07ZZ09-4-M-28 B

07ZZ09-4-M-29 C

07ZZ09-4-M-30 D

07ZZ09-4-M-31 D

07ZZ09-4-M-32 B

07ZZ09-4-M-33 B

07ZZ09-4-M-34 C


9 - 68

07ZZ09-4-M-35 C

07ZZ09-4-M-36 D

07ZZ09-4-M-37 C

07ZZ09-4-M-38 C

07ZZ09-4-M-39 A

07ZZ09-4-M-40 A

07ZZ09-4-M-41 B

07ZZ09-4-M-42 D

07ZZ09-4-M-43 B

07ZZ09-4-M-44 C

07ZZ09-4-M-45 C

07ZZ09-4-M-46 B


(a) 1s22s23s23p63d54s1

(b)(i) P: Cr(H2O4Cl2)Cl; Q: Cr(H2O)3Cl3

(ii) bonded in the horizontal plane or perpendicular to the plane

(c) The ethanedioate ion is a strong field ligand which causes a larger orbital splitting as compared to water

(d)(i) Cr2O3 2Al 2Cr Al2O3

(ii) 83.2g

07ZZ09-4-Q-02

(a)(i) Different number of electrons can be used for bond formation, leading to variable oxidation states

(ii) A is copper metal. B is aqueous CuSO4 or

Cu(H2O)62 or aqueous

Cu2

(b) In the presence of

cyanide ions, Fe3 forms a complex

[Fe(CN)6]3. The reaction is not feasible

(c)(i) Electrons from lower energy orbital absorb energy from the visible region of the electromagnetic radiation to be promoted to higher energy d orbitals

(ii) Different ligands have different capacities of splitting the 3d orbitals, hence different colour observed

07ZZ09-4-Q-03

(a)(i) Stronger ligands

stabilizes the 3 oxidation state more

(ii) Co(OH)2 (blue ppt);

Co(NH3)62 (pale brown

soln); 2Co(NH3)63

(dark brown soln)

(b) Metallic bond is stronger for chromium (higher mp) than potassium. Effective nuclear charge is larger for chromium and the electrons are more tightly held by the nucleus

07ZZ09-4-Q-04

(a) Na4FeC6N6, sodium hexacyanoferrate (II)

(b) 2Na4[Fe(CN)6] Cl2

2Na3[Fe(CN)6] 2NaCl

(c) Chlorine oxidizes Fe2

to Fe3

(d) CN or CO can act as ligands; they are strongly and irreversibly bonded to

Fe2

07ZZ09-4-Q-05

(a)(i) 1s22s22p63s23p63d3

(ii) Cr3 is relatively more

stable than Cr2

(b)(i) Cr6 polarizes the ligands such as water extensively to give

CrO42

(ii) 2H(aq) CrO42(aq)

Cr2O72(aq) H2O(l)

(c) the final oxidation

state of Cr is 2

07ZZ09-4-Q-06

(a) The EMF is more positive in alkaline conditions than in acidic conditions, hence the oxidation of

Fe2 compounds occur more readily in alkaline medium

(b) Both Mn3 and Co3 have more positive redox potentials than

Fe3

07ZZ09-4-Q-07

(a) Transition metal ions have low-lying vacant orbitals which can be used to accommodate the lone pair of electrons from the ligands, resulting in dative bond formation

(b) The d electrons absorb energy from the visible spectrum of the electromagnetic waves and are promoted to a higher energy level

(c) a yellow-green solution is observed which is a mix of the blue copper (II) ions and the yellow

[CuCl4]2. When dilute ammonia is added, a pale blue precipitate of copper (II) hydroxide is first formed which then dissolves in excess

base to give Cu(NH3)42

07ZZ09-4-Q-08

(a) Fe is a transition element which forms

Fe2 in which the d subshell is partially filled with 6 electrons.

CN are ions that have a lone pair of electrons on C atom that can form a dative bond with the central metal

ion Fe2

(b) When d-d transition of electrons takes place, radiation in the visible region of the electromagnetic spectrum corresponding to the energy gap is absorbed

07ZZ09-4-Q-09

(a) There is a gradual increase in density of the elements from scandium to copper as the relative atomic mass increases across the period

(b)(i) The first ionisation energy remains relatively invariant as it involves the removal of 4s electrons

(ii) The second electron in K to be removed is from an inner 2p orbital which is held more strongly by the nucleus

(c)(i) 2; 7

(ii) This is due to the close similarity in energy of the 4s and 3d electrons

(d)(i) the final oxidation

state of Cr is 2

(ii) The stability constant of the silver-ammonia complex is greater than that of the silver-water complex, as


9 - 69

ammonia is a stronger ligand than water

(iii) Two negatively charged ions are involved which is highly unfavourable due to electrostatic repulsion

(iv) Co3 can be used as a catalyst

(v) The d electrons absorb energy from the visible spectrum of the electromagnetic waves and are promoted to a higher energy level

07ZZ09-4-Q-10

(a)(i) 1s22s22p63s23p63d10

4s1

(ii) 1s22s22p63s23d9

(b)(i) Cu has filled 3d subshell and hence it cannot undergo d-d electron transition to absorb visible light

(ii) Cu disproportionates

to Cu2 and Cu

(c)(i) they are able to vary their oxidation states and have a partially filled 3d subshell

(ii) [Fe(CN)6]3, the negative complex ion, will not react with either the iodide ion or

the S2O82 ion due to

the electronic repulsion between them

(d) On the addition of concentrated HCl, a yellow solution of

[CuCl4]2 is observed. On the addition of excess ammonia, a deep blue solution of

[Cu(NH3)4]2 is formed

07ZZ09-4-Q-11

(a)(i)(1) a blue solution of the complex

[Ni(NH3)6]2 is formed

from [Ni(H2O)6]2. On the addition of sodium cyanide, the solution changes from blue to yellow when the

[Ni(CN)4]2 complexes are formed

(2) [Ni(NH3)6]2 4CN

[Ni(CN)4]2 6NH3

(ii) The cyanide ion is a stronger ligand as compared to ammonia, and thus causes a larger orbital splitting. Therefore the colour of the complexes differ

(b)(i) the availability of partially filled 3d subshell and the ability to vary their oxidation state

(ii) Iron provides a surface for the adsorption of the reactant molecules. This leads to an increase in reaction rate as adsorption weakens the bonds in the reactant molecule, thereby lowering the activation energy

07ZZ09-4-Q-12

(a) Chloride gives a white precipitate of silver chloride which dissolves readily in dilute aqueous ammonia to give a colourless solution. Bromide reacts with aqueous silver nitrate to give a cream precipitate of silver bromide which does not dissolve in dilute aqueous ammonia

(b)(i) The reaction between iodide and

peroxodisulphate is slow

(ii) Co is a transition metal which is able to exhibit multiple oxidation states

(iii) Co3 2I I2 2Co2;

2Co2 S2O82

2SO42 2Co3

(iv) Haber process - iron

07ZZ09-4-Q-13

(a) The bonding is a dative covalent bond. Ligands have lone pairs of electrons that can be donated to the empty orbitals of the central transition metal ion

(b)(i) Bidentate ligand is a ligand that contains two groups that have a lone pair of electrons each which can form two bonds to the central metal cation

(ii) 6

(c)(i) the orbitals in cobalt become non-degenerate when visible light falls on the compound., the electrons undergo d-d transition

07ZZ09-4-Q-14

(a)(i) Cr: 3d5 4s1; Cr3: 3d3

(ii) The transition elements form coloured compounds and complexes

(iii) Add aqueous HNO3 followed by AgNO3(aq)

(b)(i) 2Cr3 10OH

3H2O2 2CrO42

8H2O

(ii) Not a redox reaction. The oxidation state of remains the same at

6

(iii) when the effervescence stops

(iv) Acid converts CrO42

to Cr2O72, and H2O2

will react with Cr2O72

07ZZ09-4-Q-15

(i) A is colourless

(ii) B is [Cu(NH3)4]2

(iii) C is [Cu(edta)]2

(iv) D is Fe(OH)3. 2Fe(OH)2

½O2 H2O 2Fe(OH)3

(v) [Cu(edta)]2 has a higher stability constant as compared

to [Cu(NH3)4]2, therefore it will form in preference to the ammonia complex

07ZZ09-4-Q-16

(a)(i) 7.61 103 mol dm3

(ii) Fe2 ion has a smaller charge density; less

polarizing than Fe3

(b)(i) The availability of partially filled or empty 3d orbitals helps in the adsorption of reactant molecules onto the catalyst surface, weakening the bonds in the reactant molecules

(ii) Reactants are not brought together

(c) Complex D, [Fe(CN)6]4, is formed between

Fe2 and excess CN. Chlorine oxidises

[Fe(CN)6]4 to

[Fe(CN)6]3. Reaction

with I is not favoured as both are negatively charged ions

07ZZ09-4-Q-17

(a) The lone pair of the water ligands are donated to the partially filled d orbitals of the central iron (II) metal cation to


9 - 70

form Fe(H2O)62

complex

(b)(i) Transports oxygen around the body

(ii) CO is a stronger ligand than oxygen. It binds irreversibly with haemoglobin, rendering the latter ineffective

07ZZ09-4-Q-18

(a) Transition metal ions possess variable oxidation states. Transition metal ions form complexes. Transition metal ions form coloured complexes

(b)(i) When Fe3 is added

to iodide ions, I is oxidised to brown

iodine. [Fe(CN)6]3 does not oxidize iodide

ions to I. [Fe(CN)6]4 reduces brown iodine to colourless iodide

(ii) In the presence of the cyanide ligand, the iron (III) cation is stabilized with respect to iron (II) ions

(c)(i) The cyanide ligand is irreversible bonded to the iron (II) cation, preventing the bonding of the oxygen ligand to the haemoglobin

(ii) the reaction will reduce the amount of cyanide anions in the bloodstream

07ZZ09-4-Q-19

(a)(i) 6CrO2 10H

4Cr3 Cr2O72 5H2O

(ii) 33.6 %

07ZZ09-4-Q-20

(a)(i) The colour of aqueous copper (II)

cations is blue. That of magnesium (II) cations is colourless

(ii)(1) The copper (II) cations form complex ions with aqueous ammonia while magnesium (II) cations do not

(2) The copper (II) ions can oxidize iodide ions to form iodine. Magnesium (II) ions do not exist in oxidation states other than the

2 state

(b) Cu2 acts as a homogeneous catalyst by speeding up the rate of reaction. It provides an alternative mechanism with lower activation energy

07ZZ09-4-Q-21

(i) X is CoN4H12Cl3. The six ligands consist of 4 ammonia ligands and 2 chlorine ligands

(ii) 3

(iii) [Co(NH3)4Cl2]

07ZZ09-4-Q-22

(a)(i) [Fe(H2O)6]3 6CN

[Fe(CN)6]3 6H2O;

[Fe(H2O)6]3 SCN

[Fe(H2O)5(SCN)]2 H2O

(ii) Change in oxidation state from Cr(II) to Cr(III)

(b)(i) pH and ligand change

(ii) Fe2 is stabilized with

respect to Fe3 in

acidic medium. Fe3 is stabilized with respect

to Fe2 when

complexed with CN compared with H2O as ligands

07ZZ09-4-Q-23

(a)(i) Vanadium forms coloured ions. Vanadium forms compounds with variable oxidation states due to partially filled 3d orbitals

(ii) The V2 is oxidized by

H to form V3

(b) 3

07ZZ09-4-Q-24

(a)(i) Iron (II) sulphate reacts with sodium hydroxide to give a green precipitate of iron (II) hydroxide, which will oxidize in the presence of air to give a brown precipitate of iron (III) hydroxide

(ii) The redox potential of

Mn2/Mn3 is more positive than expected because the removal of an electron from

Mn3 results in a stable d5 configuration in

Mn2

(b) Fe2 can form a stable

complex of [Fe(CN)6]4

with CN

(c) 1.75 103;

[Cr(H2O)4Cl2]

07ZZ09-4-Q-25

(ii) A ligand is a neutral molecule or anion with at least one lone pair of electrons

(iii) A dative bond is formed with the central metal ion which has a vacant d orbital

(iv) A strong ligand can displace a weak ligand in a complex and this can result in a change

of colour; [Cu(H2O)6]2

< [CuCl4]2 <

[Cu(NH3)4(H2O)2]2

(b) A is [Co(NH3)4Cl2]. The oxidation number of Co in the complex ion

is 3

07ZZ09-4-Q-26

(a)(i) Co3 can oxidize water spontaneously

and is reduced to Co2

(ii) Titanium (IV) ion has no 3d electrons, thus the paint appears white. The electrons in

3d orbitals of Cr3 undergo d-d transitions, in which visible light is absorbed, leaving green as complementary colour

(b)(i) NH3, being a stronger ligand, can displace H2O from

Cu2(aq) to form a copper (II)-ammonia complex

(ii) The organic layer will be colourless while the aqueous layer will be deep blue

(iii) n 4

10 organic chemistry

10 - 95

Answer keys:

MCQs 07ZZ10-1-M-01 C

07ZZ10-1-M-02 D

07ZZ10-1-M-03 A

07ZZ10-1-M-04 C

07ZZ10-1-M-05 A

07ZZ10-1-M-06 C

07ZZ10-1-M-07 D

07ZZ10-1-M-08 C

07ZZ10-1-M-09 C

07ZZ10-1-M-10 A

07ZZ10-1-M-11 B

07ZZ10-1-M-12 C

07ZZ10-1-M-13 A

07ZZ10-1-M-14 C

07ZZ10-1-M-15 D

07ZZ10-1-M-16 D

07ZZ10-1-M-17 A

07ZZ10-1-M-18 B

07ZZ10-1-M-19 A

07ZZ10-1-M-20 D

07ZZ10-1-M-21 D

07ZZ10-1-M-22 A

07ZZ10-1-M-23 B

07ZZ10-1-M-24 D

07ZZ10-1-M-25 D

07ZZ10-1-M-26 B

07ZZ10-1-M-27 B

07ZZ10-1-M-28 B

07ZZ10-1-M-29 A

07ZZ10-1-M-30 D

07ZZ10-1-M-31 C

07ZZ10-1-M-32 B

07ZZ10-1-M-33 C


(a) TMS as an internal reference and is the zero point of the

(ppm) scale. D2O is to identify the labile protons

(b)(i)(I) M

(II) P and O

(III) It will split into a doublet by the single, adjacent H atom labelled N

(c) NMR spectroscopy cannot be used to distinguish between optical isomers

07ZZ10-1-Q-02

Geometric isomerism and optical isomerism

07ZZ10-1-Q-03

(i) 6

(ii) 15.2 cm3

07ZZ10-1-Q-05

(ii) It may cause side effects; it is not useful as a drug

07ZZ10-1-Q-06

(a) Stereoisomerism is exhibited when different compounds have the same molecular and structural formula but different spatial arrangements

(b) Geometric isomerism

(c)(iii) The isomers are distinguished by the rotation of the plane of polarized light

07ZZ10-1-Q-07

In Q, each of the C atoms in the carbon-carbon double bonds contains different groups. In R, there are two same (H) groups on the same C atom in the carbon-carbon double bond

07ZZ10-1-Q-08

Four structural isomers are possible for alcohols with the molecular formula C4H10O

07ZZ10-1-Q-10

(i) CH2

(iv) The optical isomerism is due to the presence of a chiral carbon, non-superimposable mirror images and no plane of symmetry

07ZZ10-1-Q-11

(a) Tetrachloromethane does not contain any protons, therefore it does not give a signal in the NMR spectrum

(b) All the twelve protons in TMS are chemically equivalent, thus resonate as the same frequency to give only 1 signal

(c)(i) Propan-1-ol: 4 signals; Propan-2-ol: 3 signals

(ii) Propanal: 3 signals; Propanone: 1 signal


07ZZ10-2-M-02 D

07ZZ10-2-M-03 C

07ZZ10-2-M-04 D

07ZZ10-2-M-05 A

07ZZ10-2-M-06 C

07ZZ10-2-M-07 B

07ZZ10-2-M-08 C

07ZZ10-2-M-09 D

07ZZ10-2-M-10 B

07ZZ10-2-M-11 D

07ZZ10-2-M-12 A

07ZZ10-2-M-13 B

07ZZ10-2-M-14 C

07ZZ10-2-M-15 C

07ZZ10-2-M-16 A

07ZZ10-2-M-17 D

07ZZ10-2-M-18 D

07ZZ10-2-M-19 B

07ZZ10-2-M-20 A

07ZZ10-2-M-21 A

07ZZ10-2-M-22 C

07ZZ10-2-M-23 B

07ZZ10-2-M-24 A

07ZZ10-2-M-25 C

07ZZ10-2-M-26 C

07ZZ10-2-M-27 B

07ZZ10-2-M-28 D

07ZZ10-2-M-29 C

07ZZ10-2-M-30 D

07ZZ10-2-M-31 D

07ZZ10-2-M-32 C

07ZZ10-2-M-33 C

07ZZ10-2-M-34 C

07ZZ10-2-M-35 C

07ZZ10-2-M-36 D

07ZZ10-2-M-37 A

07ZZ10-2-M-38 D

07ZZ10-2-M-39 B


10 - 96

07ZZ10-2-M-40 A

07ZZ10-2-M-41 C

07ZZ10-2-M-42 B

07ZZ10-2-M-43 B

07ZZ10-2-M-44 C

07ZZ10-2-M-45 C

07ZZ10-2-M-46 D

07ZZ10-2-M-47 C

07ZZ10-2-M-48 B


(ii) Isomer X will not decolourise aqueous bromine

07ZZ10-2-Q-02

(i) I: addition polymerization; II: oxidation

07ZZ10-2-Q-03

(a)(i) I: H2O, concentrated H3PO4, 300oC; II: concentrated HNO3, concentrated H2SO4, 50-60oC

(ii) The presence of the electrons on the aromatic ring and the carbon-carbon double bond makes styrene electron rich

(b)(i) elimination

(ii) Br2, absence of uv light

07ZZ10-2-Q-04

(i) electrophilic substitution

(ii) A large proportion of

CH3CH2CH2

carbocations undergoes a rearrangement to the more stable secondary

carbocations (CH3)2CH

07ZZ10-2-Q-05

(i) CH3COOH and

HOOCCHClCH2NH3

(ii) CH3CH2CH2CHClCH2CH2

NH2

07ZZ10-2-Q-06

B (C5H8O3); C (C4H6O4); D (Acid chloride); E (Ester)

07ZZ10-2-Q-07

Hydrogen bromide reacts with propene via the electrophilic addition reaction. The major product is formed due to a more stable 2° carbocation (it has more electron-donating alkyl groups) as compared to the 1° carbocation

07ZZ10-2-Q-08

To get L: conc. HNO3/ conc. H2SO4, 30oC; To get M: Br2, FeBr3; To get final product: KMnO4 acidified with H2SO4, heat under reflux

07ZZ10-2-Q-09

(b) (a)(ii) has the highest boiling point

07ZZ10-2-Q-10

(a) electrophilic addition

(d) aqueous KOH, heat

(e)(i) the reaction rate will increase

(ii) No reaction

07ZZ10-2-Q-11

(b)(i) geometric isomerism

(c)(i) optical isomerism

(d) The reaction forms racemic mixture. Intermediate carbocation which is trigonal planar in shape can be attacked

from either side of the plane to create both enantiomers

07ZZ10-2-Q-12

(b) C10H22 C4H10 C4H8

C2H4

(c) BrBr 2Br•

CH3CH2CH2CH3 Br•

CH3CH2CH2CH2 HBr

CH3CH2CH2CH2 Br2

CH3CH2CH2CH2Br Br•

CH3CH2CH2CH2 Br• CH3CH2CH2CH2Br

Br• Br• Br2

07ZZ10-2-Q-14

add acidified KMnO4, reflux

07ZZ10-2-Q-15

(a)(ii) Addition polymerization

(ii) Restricted rotation about the double bonds of the polymer; inflexible

(b)(ii) Condensation polymerization. Ester linkages are formed

07ZZ10-2-Q-17

(i) OH, CH3

(ii) CO2C2H5, NO2

07ZZ10-2-Q-18

(a)(i) CH3(CH2)8CH3 CH4

C3H8 C6H10

(ii) 90 kJ mol1

(b) CFCs produce chlorine radicals, which may lead to ozone depletion

(c)(ii) Reaction 1: uv light; Reaction 2: FeCl3 catalyst, dark

07ZZ10-2-Q-19

H (cyclohexa-1, 3, 5-

triene) 360 kJ mol1

07ZZ10-2-Q-20

(b)(i) absence of uv light, room temperature;

(ii) Mechanism of electrophilic addition

07ZZ10-2-Q-21

Electrophilic addition reaction


07ZZ10-3-M-02 D

07ZZ10-3-M-03 D

07ZZ10-3-M-04 A

07ZZ10-3-M-05 B

07ZZ10-3-M-06 B

07ZZ10-3-M-07 D

07ZZ10-3-M-08 C

07ZZ10-3-M-09 C

07ZZ10-3-M-10 B

07ZZ10-3-M-11 B

07ZZ10-3-M-12 C

07ZZ10-3-M-13 C

07ZZ10-3-M-14 B

07ZZ10-3-M-15 B

07ZZ10-3-M-16 D

07ZZ10-3-M-17 A

07ZZ10-3-M-18 A

07ZZ10-3-M-19 C

07ZZ10-3-M-20 A

07ZZ10-3-M-21 B

07ZZ10-3-M-22 A

07ZZ10-3-M-23 D

07ZZ10-3-M-24 D

07ZZ10-3-M-25 B

07ZZ10-3-M-26 B


10 - 97

07ZZ10-3-M-27 D

07ZZ10-3-M-28 D


(ii) NH3 is an electron rich nucleophile

07ZZ10-3-Q-03

(i) The reaction is second order. This is a nucleophilic substitution reaction

(ii) k2 > k1 > k3

(iii) warm each of the unknown with aqueous NaOH in separate test tubes, and add excess dilute HNO3 followed by aqueous AgNO3 to each of them

07ZZ10-3-Q-04

P to Q: nucleophilic substitution; Q to R: oxidization of ketone; R to S: nucleophilic addition; S to T: Reduction of nitrile group; T to U: nucleophilic substitution

07ZZ10-3-Q-05

(i) Nucleophilic substitution

07ZZ10-3-Q-06

add NaOH (aq), reflux. Add HNO3 (aq) to neutralize excess NaOH (aq). Then add AgNO3(aq)

07ZZ10-3-Q-07

(ii) Condensation reaction

07ZZ10-3-Q-08

NaOH (aq), warm; followed by dilute HNO3 and then AgNO3

07ZZ10-3-Q-09

NaOH (aq), warm; followed by dilute HNO3 and then AgNO3

07ZZ10-3-Q-10

HBr, room temperature; conc. NH3, reflux under pressure

07ZZ10-3-Q-11

(a) Nucleophilic substitution

(b) G undergoes nucleophilic substitution with aqueous sodium hydroxide to give an alcohol functional group in H; Acidification of H gives I; I undergoes substitution with PCl5 to give J; J undergoes nucleophilic substitution with ammonia to form amide, K

07ZZ10-3-Q-12

(a) Step 1: limited Cl2(g), UV light; Step 2: Cl2, AlCl3, anhydrous conditions

(b) Heat compound E and F with NaOH (aq), acidify with HNO3 and add AgNO3. White precipitate observed with E and not F

(c) Free-radical substitution

07ZZ10-3-Q-14

A to B: replacement of bromine atom by hydroxyl group; B to C: oxidaztion of secondary

alcohol to form a ketone; B to D: CH3CH(OH) group in B reacts with sodium hydroxide and iodine to give D; B to E: B is mono-substituted, and undergoes strong oxidation to form E


07ZZ10-4-M-02 B

07ZZ10-4-M-03 D

07ZZ10-4-M-04 A

07ZZ10-4-M-05 B

07ZZ10-4-M-06 B

07ZZ10-4-M-07 A

07ZZ10-4-M-08 B

07ZZ10-4-M-09 C

07ZZ10-4-M-10 D

07ZZ10-4-M-11 C

07ZZ10-4-M-12 D

07ZZ10-4-M-13 C

07ZZ10-4-M-14 B

07ZZ10-4-M-15 D

07ZZ10-4-M-16 D

07ZZ10-4-M-17 D

07ZZ10-4-M-18 B

07ZZ10-4-M-19 A

07ZZ10-4-M-20 D

07ZZ10-4-M-21 D

07ZZ10-4-M-22 D

07ZZ10-4-M-23 A

07ZZ10-4-M-24 D

07ZZ10-4-M-25 D

07ZZ10-4-M-26 C

07ZZ10-4-M-27 C

07ZZ10-4-M-28 B

07ZZ10-4-M-29 C

07ZZ10-4-M-30 D

07ZZ10-4-M-31 A

07ZZ10-4-M-32 A

07ZZ10-4-M-33 B

07ZZ10-4-M-34 C

07ZZ10-4-M-35 C

07ZZ10-4-M-36 B


(a) The phenol group in W can undergo acid-base reaction with aqueous sodium hydroxide to give an ionic salt which ionizes readily in water

(c) Optical isomerism

07ZZ10-4-Q-02

(a) As the molecular mass of the alcohols increase, the alcohols have a greater number of electrons. This leads to stronger temporary dipole-induced dipole attractions

(b) Orsellinic acid is polar in nature. The acid and alcohol groups present are able to form hydrogen bonds with the butanol molecules

07ZZ10-4-Q-03

Warm with alkaline aqueous iodine

07ZZ10-4-Q-04

L to M: when refluxed with aqueous potassium dichromate (VI), the alcohol group is oxidized to carboxylic acid; M to N: on


10 - 98

addition of SOCl2; N to P: undergoes cyclisation

07ZZ10-4-Q-05

conc. H2SO4 170°C; HCl(g); NH3 in ethanol, heat in a sealed tube

07ZZ10-4-Q-06

(i)(I) To each compound in a test tube, add PCl5 in the cold. H is present when white fumes of hydrogen chloride are observed

(II) Add dilute NaOH and heat. Then add dilute HNO3 and aqueous AgNO3. G is present when white precipitate of AgCl is formed

(ii) F is a stronger acid than G

07ZZ10-4-Q-07

In aqueous medium, the phenoxide ion is more reactive towards electrophilic substitution as there is a greater delocalisation of electrons into the benzene ring due to the negative charge. A tribrominated product thus forms when phenol reacts with aqueous bromine

07ZZ10-4-Q-08

(i) K has an alcohol, OH group. L contains a carbonyl functional group. K contains the CH3CH(OH) group and L the CH3CO group. M contains two chiral carbon atoms

(ii) It is a meso compound with non-superimposable mirror images

07ZZ10-4-Q-09

(b) I: NaOH (alc), reflux; II: H2O, H3PO4, 300oC, 60 atm; III: NaOH (aq), reflux

(c) H2SO4 NaI HI NaHSO4; HI produced is readily oxidized by conc. sulphuric acid to I2. H3PO4 is used instead to react with NaI

07ZZ10-4-Q-10

Br2 (aq) or neutral FeCl3

07ZZ10-4-Q-11

(a)(i) Presence of excess CH3Cl allows amine to perform multiple nucleophilic substitutions to form the quarternary ammonium salt

(b)(ii) NaOH (aq), I2 (aq), warm

07ZZ10-4-Q-12

(b) electrophilic addition

(c) Br2 (l), FeBr3

07ZZ10-4-Q-14

(a) propan-2-ol; propane-1, 2-diol

(b) Pathway A: steam, H3PO4 catalyst, 70 atm, 300oC; Pathway B: KMnO4, alkaline, cold, dilute

07ZZ10-4-Q-15

acidified K2Cr2O7, warm

07ZZ10-4-Q-17

Aqueous alkaline iodine, warm

07ZZ10-4-Q-18

Stage I: LiAlH4 in dry ether at room temperature; Stage II: concentrated H2SO4 at

180oC; A: (CH3)2CHCH2OH

07ZZ10-4-Q-19

dilute HCl, reflux; followed by KMnO4, reflux

07ZZ10-4-Q-20

(i) Reaction I: excess NH3, high temperature and pressure; Reaction II: PCl5, room temperature

(ii) Nucleophilic substitution


07ZZ10-5-M-02 C

07ZZ10-5-M-03 B

07ZZ10-5-M-04 D

07ZZ10-5-M-05 C

07ZZ10-5-M-06 A

07ZZ10-5-M-07 B

07ZZ10-5-M-08 B

07ZZ10-5-M-09 A

07ZZ10-5-M-10 D

07ZZ10-5-M-11 C

07ZZ10-5-M-12 C

07ZZ10-5-M-13 A

07ZZ10-5-M-14 D

07ZZ10-5-M-15 D

07ZZ10-5-M-16 B

07ZZ10-5-M-17 A

07ZZ10-5-M-18 B

07ZZ10-5-M-19 A

07ZZ10-5-M-20 A

07ZZ10-5-M-21 A

07ZZ10-5-M-22 B

07ZZ10-5-M-23 C

07ZZ10-5-M-24 D

07ZZ10-5-M-25 C

07ZZ10-5-M-26 D

07ZZ10-5-M-27 B

07ZZ10-5-M-28 A


(iii) condensation reaction

(iv) Non-planar as the CH3 group is tetrahedrally hybridized

(vi) geometric isomerism

07ZZ10-5-Q-02

Step 1: LiAlH4, dry ether; Step 2: KCN, ethanol, reflux; Step 3: NaOH, reflux; Step 4: Sn, concentrated HCl, reflux; Step 5: conc HNO3, conc H2SO4, reflux

07ZZ10-5-Q-03

(i) The OH group in glucose is able to form intermolecular hydrogen bonds with water

(ii) Glucose is a reducing sugar as it contains an aldehyde functional group, showing reducing property with reagents like Fehling’s or Tollens’

07ZZ10-5-Q-04

warm with Fehling’s solution

07ZZ10-5-Q-05

warm with Tollens’ reagent


10 - 99

07ZZ10-5-Q-06

HCN reacts with ethanal via a nucleophilic addition reaction, forming an equimolar mixture of the two optical isomers and hence the product is optically inactive

07ZZ10-5-Q-07

A is a secondary alcohol. A, B, C or D reacts separately with hot acidified potassium manganate (VII), leading to the oxidation of the side chain

07ZZ10-5-Q-08

(i) H contains a phenolic group

(ii) J contains an aromatic aldehyde group

07ZZ10-5-Q-09

(a) Red precipitate of Cu2O observed

(c) Addition polymerization

07ZZ10-5-Q-10

add 2, 4-dinitrophenylhydrazine

07ZZ10-5-Q-12

(a)(ii) HCl (g)

(iii) electrophilic addition

(b)(ii) Reaction II: acidified potassium dichromate (VI), reflux; Reaction

III: HCN, trace of CN

07ZZ10-5-Q-13

2, 4-dinitrophenylhydrazine, room temperature

07ZZ10-5-Q-14

Tollens’ reagent

07ZZ10-5-Q-15

G is produced from the mild oxidation of F. Therefore F must be an alkene. C is a halogenoalkane which reacts with potassium hydroxide in a nucleophilic substitution to produce an alcohol, D. Since D is a secondary alcohol, mild oxidation produces a ketone, E.

07ZZ10-5-Q-16

Test 1: add Tollens’ reagent to the 3 unknown compounds separately. Heat the mixture; Test 2: add 2, 4-dinitrophenylhydrazine to the other 2 unknown compounds separately. Heat the mixture; Test 3: add bromine in CCl4 in the absence of light to the last compound

07ZZ10-5-Q-17

(a) Reduction

(b) Condensation

(c) Electrophilic addition; Geometric or optical isomerism

(d) Nucleophilic addition; Optical isomerism

07ZZ10-5-Q-18

(b) A is an alkyl halide undergoing elimination to give an alkene, B. The carbon-carbon double bond in B cleaves to give two products on oxidation. C is an aldehyde (propanal) or ketone (propanone) undergoing nucleophilic addition with HCN to form D.

Since D is optically active, C is propanal


07ZZ10-6-M-02 C

07ZZ10-6-M-03 D

07ZZ10-6-M-04 B

07ZZ10-6-M-05 D

07ZZ10-6-M-06 B

07ZZ10-6-M-07 D

07ZZ10-6-M-08 A

07ZZ10-6-M-09 D

07ZZ10-6-M-10 B

07ZZ10-6-M-11 D

07ZZ10-6-M-12 D

07ZZ10-6-M-13 A

07ZZ10-6-M-14 C

07ZZ10-6-M-15 C

07ZZ10-6-M-16 B

07ZZ10-6-M-17 C

07ZZ10-6-M-18 B

07ZZ10-6-M-19 A

07ZZ10-6-M-20 D

07ZZ10-6-M-21 B

07ZZ10-6-M-22 A

07ZZ10-6-M-23 C

07ZZ10-6-M-24 C

07ZZ10-6-M-25 C

07ZZ10-6-M-26 B

07ZZ10-6-M-27 B

07ZZ10-6-M-28 B

07ZZ10-6-M-29 D

07ZZ10-6-M-30 B

07ZZ10-6-M-31 D

07ZZ10-6-M-32 D

07ZZ10-6-M-33 B

07ZZ10-6-M-34 C

07ZZ10-6-M-35 C

07ZZ10-6-M-36 C

07ZZ10-6-M-37 B

07ZZ10-6-M-38 C

07ZZ10-6-M-39 D


(i) I: concentrated HNO2, concentrated H2SO4,

warm; II: MnO4/H,

reflux; III: PCl5; IV: Bromine water at rt; V: HN(CH3)2 and heat; VII: Sn/ c HCl, heat

(ii) condensation reaction

07ZZ10-6-Q-02

(a)(i) Propanoic acid forms strong intermolecular hydrogen bonding which are more extensive than that of butan-1-ol

(ii) Butan-1-ol forms hydrogen bonding between molecules while ethoxyethane forms weak van der Waals’ forces between molecules

(b) Boiling point: any values below 36oC or about 10oC; It has weaker van der Waals’ forces of attraction between molecules

(d) Ethoxyethane is a non-polar molecule, thus it is not soluble in water

07ZZ10-6-Q-03

(a) X: potassium dichromate (VI) and H2SO4; Y: sodium


10 - 100

metal; Z: phosphorous pentachloride

(b) ethanoic acid

(d) F has an ionic structure

(e) Addition of HCN at room temperature to ethanal, then hydrolyse the product with boiling dilute H2SO4 and reflux

07ZZ10-6-Q-04

(b) Add I2 and NaOH(aq) to each sample in a test tube and warm

(c) Add HCN/OH at 10-20oC to ethanal to form CH3CH(OH)(CN)

and then add H, reflux to form M

(d)(i) M, a hydroxyl-acid, forms hydrogen bonds while N, an amino acid, forms ionic bonds which are stronger

(ii) M is a stronger acid due to the presence of electronegative O in

the OH group

07ZZ10-6-Q-05

(a)(ii) Weak acids are only partially ionized in solution

(b)(i) 3: add drops of conc. H2SO4 into mixture as catalyst; 4: heat the mixture

(ii) The paper serves as a condenser to reduce evaporation loss of unreacted alcohol, acid, and ester

07ZZ10-6-Q-06

(a)(i) orange precipitate formed

(ii) a clear solution formed

(b) acidified potassium dichromate (VI), distill

07ZZ10-6-Q-07

(a) I: anhydrous phosphorous pentachloride at room conditions; II: ammonia gas in sealed tube; III: aqueous potassium manganate (VII)/ aqueous sulphuric acid, reflux

(b) The OH group in X reacts with aqueous bromine and sodium metal to form a tribrominated product and a salt respectively; E is formed as a result of the esterification reaction between X and CH3CH2COCl in alkaline medium. The

OH group in Y reacts with sodium metal; F is formed as a result of the esterification reaction between Y and CH3COOH using concentrated sulphuric acid as a catalyst

07ZZ10-6-Q-08

dilute NaOH (aq), warm; followed by NaOH(aq), I2

07ZZ10-6-Q-09

(a)(i) I: Cl2, FeCl3; II: SOCl2; III: Cl2 (CCl4), uv light

(ii) H2O; KOH (alc), 1 mol H2/Pt

(iii) The CX bond in P has a partial double bond character. Hence, it is harder to break this strengthened bond

(b) The benzoic anion is more stable than phenoxide. For bromination, the mechanism involved is electrophilic substitution. Therefore, phenol

reacts very readily with Br2 /CCl4, whereas benzenecarboxylic acid reacts only in the presence of a Lewis acid catalyst such as FeBr3

07ZZ10-6-Q-11

CH3COOH CH3COO

H

CH3CH2COOH

CH3CH2COO H

FCH2COOH

FCH2COO H

The strength of the acid is determined by the stability of the conjugate base. 2-fluoroethanoic acid > ethanoic acid > propanoic acid

07ZZ10-6-Q-12

Compound P is sparingly soluble in water but readily soluble in aqueous sodium hydroxide. This shows that P has

COOH group and a large hydrophobic group

Compound S has a carbon-carbon double bond with two different substituents on each carbon of the double bond as it exhibits cis-trans isomerism

S undergoes strong oxidation with acidified potassium manganate to give T, C3H4O4, and ethanoic acid. The carbon-carbon double bond is cleaved and is located between the second and third carbon in the carbon chain of S

One mole of T reacts with excess sodium carbonate to give one mole of carbon dioxide. T is thus a dicarboxylic acid

Q can react with aqueous alkaline iodine to give a yellow precipitate. Q has a

CH3CH(OH)R group where R is an aliphatic group. Q undergoes dehydration to form S which has a carbon-carbon double bond

Q underwent self-esterification to form ester R as R is a sweet smelling liquid

P undergoes nucleophilic substitution with sodium hydroxide to give Q which will have an alcohol group on it

07ZZ10-6-Q-13

(a) C11H13O2Cl has a high C:H ratio, thus the compound may contain a benzene ring. R reacts with aqueous sodium hydroxide to give two immiscible liquids due to the hydrolysis of the ester bond present. There is no nitrogen atom in the compound, thus there is no amide bond. Oxidation of T gives benzoic acid, thus T is phenylmethanol. S is optically active and thus has a chiral carbon. S reacts with aqueous alkaline iodine thus it has either the CH3CH(OH) or CH3CO group

(b) Phenyl chloride < Phenylmethyl chloride < Benzoyl chloride


10 - 101

07ZZ10-6-Q-14

P: ethanol benzoic acid; concentrated H2SO4, reflux

Q: phenol ethanoyl chloride, room temperature

07ZZ10-6-Q-15

A is CH3CH2Br; B is CH3CH2CH2OH

Step I: Br2, UV; Step II: NaCN (alc), heat under

reflux; Step III: H (aq), heat under reflux; Step IV: LiAlH4, dry ether, heat under reflux

(followed by H(aq), room temperature); Step V: PCl5, room temperature

07ZZ10-6-Q-16

Carboxylic acid has a smaller pKa (higher acid strength) than phenol group

2RCOOH Na2CO3

2RCOONa H2O CO2

07ZZ10-6-Q-17

(a)(iii) Increases the solubility of drugs

(b)(i) Br2 in non-polar solvent, FeBr3 catalyst

(c) Test: add 2, 4-dinitrophenylhydrazine to both compounds; Observations: Naproxen will not give a precipitate while Ketoprofen will give a yellow precipitate

07ZZ10-6-Q-18

(a) CH3CHClCO2H > CH2ClCH2CO2H > CH3CH2CO2H > ClC6H4OH

(b)(ii) Step I: conc. H2SO4, 170oC; Step II: acidified

KMnO4, heat; Step III: acidified K2Cr2O7, reflux

(c) The ketone formed in step III is planar at the

CO group, thus, resulting in a racemic mixture

07ZZ10-6-Q-19

(ii) Positional isomerism

(iii) B undergoes nucleophilic substitution releasing

Br ions, which react with AgNO3 to form AgBr (pale yellow precipitate); In C, the Br atom very difficult to displace from the benzene ring. Thus no AgBr precipitate is formed

(iv) I2 (aq) / NaOH(aq) followed by HCl, heat

07ZZ10-6-Q-20

Reagents and conditions: I: Cl2 in CCl4, room temperature, dark; II: KCN (alc), heat

A: CH2(Cl)CH2(Cl); B: CH2(CN)CH2(CN)

07ZZ10-6-Q-21

Since the number of carbon and hydrogen atoms are comparable in A, and A is sparingly soluble in water, A must contain the benzene ring.

When iron (III) chloride was added to A, a purple complex was formed. This shows that A contains a phenol group.

A also decolourised aqueous bromine to form B, C9H8O3Br2. This shows that the phenol

group in A is 1, 2- or 1, 4- disubstituted.

A did not form any reddish-brown precipitate when warmed with Fehling’s solution nor did it give any silver deposits with ammoniacal silver nitrate solution. Therefore the aldehyde group is absent in A.

When A was boiled with aqueous sodium hydroxide, C, C7H4O3Na2, and ethanol were formed. Alkaline hydrolysis occurred. The ester group is present in A.

C subsequently formed D, C7H6O3, when acidified with concentrated hydrochloric acid. Thus

D contains one COOH group and one phenol group.

07ZZ10-6-Q-22

Since the number of carbon and hydrogen atoms are comparable in F, and F is sparingly soluble in water, F must contain the benzene ring. F is neutral and thus does not contain the phenol and carboxylic acid groups. F did not form any reddish-brown precipitate when warmed with Fehling’s solution. There is no aliphatic aldehyde group present. F gave silver deposits when warmed with ammoniacal silver nitrate solution. This shows that F contains an aromatic aldehyde group.

When F was boiled with aqueous sodium hydroxide, G, C8H5O3Na, and ethanol were formed. Alkaline hydrolysis occurred. This shows that the ester group is present in F.

G subsequently gave H, C8H6O3, when acidified with concentrated hydrochloric acid. Therefore H contains

one COOH group.

F was oxidized by boiling under reflux with acidified KMnO4 to give I, C8H6O4.

07ZZ10-6-Q-23

(i) I: acidified potassium dichromate (VI), heat and distill; II: HCN in presence of NaCN; III: dilute acid, heat

07ZZ10-6-Q-24

HCN, traces of NaOH, room temperature; LiAlH4 in dry ether, room temperature


07ZZ10-7-M-02 C

07ZZ10-7-M-03 B

07ZZ10-7-M-04 D

07ZZ10-7-M-05 A

07ZZ10-7-M-06 C

07ZZ10-7-M-07 C

07ZZ10-7-M-08 A

07ZZ10-7-M-09 B

07ZZ10-7-M-10 C

07ZZ10-7-M-11 C


10 - 102

07ZZ10-7-M-12 B

07ZZ10-7-M-13 B

07ZZ10-7-M-14 A

07ZZ10-7-M-15 A

07ZZ10-7-M-16 A

07ZZ10-7-M-17 A

07ZZ10-7-M-18 B

07ZZ10-7-M-19 C

07ZZ10-7-M-20 B

07ZZ10-7-M-21 B

07ZZ10-7-M-22 A

07ZZ10-7-M-23 A

07ZZ10-7-M-24 A

07ZZ10-7-M-25 B

07ZZ10-7-M-26 D

07ZZ10-7-M-27 C

07ZZ10-7-M-28 D

07ZZ10-7-M-29 A

07ZZ10-7-M-30 C

07ZZ10-7-M-31 A

07ZZ10-7-M-32 A

07ZZ10-7-M-33 D

07ZZ10-7-M-34 A

07ZZ10-7-M-35 C

07ZZ10-7-M-36 B

07ZZ10-7-M-37 A

07ZZ10-7-M-38 B

07ZZ10-7-M-39 A

07ZZ10-7-M-40 C

07ZZ10-7-M-41 B

07ZZ10-7-M-42 A

07ZZ10-7-M-43 D

07ZZ10-7-M-44 A

07ZZ10-7-M-45 B


(i) The molecule will move towards the cathode

(ii) NH2CH(CH2OH)COOH

OH

NH2CH(CH2OH)COO H2O

(iii) Amide or peptide bond

(iv) Condensation polymerization

07ZZ10-7-Q-02

(i) heat under reflux in NaOH(aq)

(ii) Lysine:blue; Alanine: green; Glutamic acid: red

(iii) 6 ways

07ZZ10-7-Q-03

(a)(i) C10H14N2

(ii) amine

(iv) Nucleophilic substitution

(b) The nitrogen atom attached to the methyl group is attached to three alkyl groups which are electron releasing. This makes its lone pair of electrons more available, and hence stabilizing the conjugate acid by dispersing the positive charge on the nitrogen atom

07ZZ10-7-Q-04

(a)(i) Tertiary amines and benzene ring

(iii) Petrol is a non-polar solvent, hence it can form dispersion forces with cocaine. Dilute hydrochloric acid can react with the amine functional group to

form a salt, which can then dissolve in the acid through ion-dipole interaction

(b)(ii) Intermediate U will further substitute excess CH3CH2Cl to form 3° or 4° amine. Intermediate U contains N atom that has a lone pair to enable it to act as a nucleophile to further substitute the Cl atom in excess CH3CH2Cl.

07ZZ10-7-Q-05

(i) A is a stronger base than B

(ii) A: The activated benzene ring due to the amine group allows the electrophilic substitution with aqueous bromine, thus it decolourises Br2(aq) and a white solid is formed

B: The amide undergoes base hydrolysis when heated with NaOH(aq), ammonia gas evolved turns red litmus blue

C: The methyl ketone undergoes positive tri-iodomethane reaction on warming with iodine in aqueous NaOH, yellow precipitate of CHI3 is formed

D: The aldehyde is oxidized by a mild oxidizing agent. On warming with ammoniacal solution of silver nitrate, silver deposits will be seen

07ZZ10-7-Q-06

(b) Phenylamine is very reactive as N atom

donates a lone pair of electrons into the ring, resulting in an electron rich benzene ring, which is highly susceptible to electrophilic attack. In the presence of dilute sulphuric acid, the

basic NH2 group is protonated to form

NH3. Hence

substituent no longer donates electrons into the ring

07ZZ10-7-Q-07

(i) The possible tripeptide combinations are GHI, GIH, HGI, HIG, IGH and IHG

07ZZ10-7-Q-08

Ethylamine is a stronger base than ammonia because the electron-donating ethyl group increases the electron density on the N atom, making the lone pair of electrons more available to accept a proton via dative bonding

Phenylamine is a much weaker base than ammonia because of the delocalisation of the lone pair of electrons on the N atom over the aromatic ring, making it less available to accept a proton via dative bond

07ZZ10-7-Q-09

Wrong: (1) a halogen carrier such as AlCl3 is required for electrophilic substitution to occur

Wrong: (2) the arene-Cl bond is too strong to be broken for


10 - 103

nucleophilic substitution to occur

Wrong: (3) the amine group activates the benzene ring, thus forming a tribrominated product instead

07ZZ10-7-Q-10

(a) B: Step 1: Sn, conc. HCl, reflux; Step 2: CH3Cl, heat with excess X in sealed tube

C: Step 1: KMnO4/H, reflux; Step 2: PCl5, cold; Step 3: NH2CH2CH2CO2H, cold

07ZZ10-7-Q-11

Compound W has a high carbon to hydrogen ratio, thus W is aromatic in nature. W can exhibit cis-trans isomerism and decolourises bromine water to produce Z, thus W has a carbon-carbon double bond with two different substituents bonded to the two carbon atoms of the double bond

W can react with Tollens’ reagents but not Fehling’s solution, thus W has an aldehyde group directly bonded to the benzene ring

X reacts with sodium

metal, thus X has a OH group present. It is a primary alcohol group as it is reduced from W which has an aldehyde group

X is readily soluble in acid, thus X probably has an alkaline amine group on it. W could be a nitrile as it is reduced to give X

W is hydrolysed by sodium hydroxide to produce Y which has a crystalline structure, thus Y is ionic in nature and is probably a sodium salt of an acid. The group containing N in W is hydrolysed into a carboxylate group. This confirms that W is a nitrile

07ZZ10-7-Q-12

(i) Since E reacts with hot aqueous hydroxide ions to give ammonia, it is most probably an amide, RCONH2

(ii) The reaction of the compound C6H7N with aqueous bromine to give a white precipitate indicates that the compound could be phenylamine

(iii) Since the compound does not react with aqueous bromine at room temperature, G is a saturated hydrocarbon or suitable structural isomers of cyclohexane

07ZZ10-7-Q-13

(c) Condensation polymerization

07ZZ10-7-Q-14

(a)(i) Step 1: NaCN (aq), ethanol, heat under reflux; Step 2: LiAlH4, dry ether; Step 3: dilute H2SO4(aq), heat under reflux

(iii) There are 6 carbons in each of the two monomers

(iv) At room temperature, the hydrogen bonding

between the CO and

NH groups between polymer chains are relatively strong, preventing polymer chains from sliding over one another. As the temperature is raised, the chains gain energy and the hydrogen bonding is weakened. The polymer chains can then slide over one another

(b)(ii) Addition polymerization

(c) Polystyrene is suitable since it will not undergo hydrolysis. However, nylon-6, 6 contains amide groups which can undergo alkaline hydrolysis with aqueous sodium hydroxide

07ZZ10-7-Q-15

II: Sn, conc. HCl, reflux; III: acidified KMnO4, reflux; IV: C2H5OH, reflux with conc. H2SO4 catalyst

07ZZ10-7-Q-16

(ii) Condensation polymerization

(iii) Adjacent strands of polymer Y are held together by strong hydrogen bonds whereas weak van der Waals’ forces of attraction hold the adjacent strands of polymer Z together

(iv) The monomers are HOCH2CH(CH3)OH and HOOCCH2CH2COOH

07ZZ10-7-Q-17

(a)(i) concentrated HNO3, concentrated H2SO4, 30oC

(ii) Electrophilic substitution

(b)(ii) II: Sn, conc. HCl, reflux, followed by NaOH(aq); III: CH3COCl, room temperature

(iii) Condensation reaction

07ZZ10-7-Q-18

(i) I: hot acidified KMnO4 (aq); II: conc. HNO3 and conc. H2SO4, temperature > 60oC; III: Sn / conc. HCl

07ZZ10-7-Q-19

H is an aromatic compound. H is weakly basic, thus it contains the amine group which could be attached to the benzene ring.

H dissolves in dilute hydrochloric acid to give a crystalline salt, J.

H decolourises aqueous bromine with the formation of a white precipitate K.

When H is heated with alkaline aqueous iodine and then followed by careful acidification, some yellow crystals are produced together with L, C7H7NO2. Thus H contains the CH3CH(OH) or methyl ketone group.

Since H does not form yellow crystals when 2, 4-dinitrophenylhydrazine is added, H is not a carbonyl compound

H contains the CH3CH(OH) group in its structure. 4-nitromethylbenzene is first heated with tin in the presence of concentrated


10 - 104

hydrochloric acid to

form M, thus the NO2 group is reduced to

give the NH2 group in M. M is then oxidized by adding hot acidified potassium manganate (VII) to produce L, therefore L contains a

COOH group due to the oxidation of the methyl group in M

07ZZ10-7-Q-20

In order of decreasing basicity: M > K > L


10 - 105

Group

IA IIA IIIB IVB VB VIB VIIB VIIIB IB IIB IIIA IVA VA VIA VIIA 0

1

1

H Hydrogen

1.0079

2

He Helium

4.0026

2

3

Li Lithium

6.941

4

Be Beryllium

9.0122

5

B Boron

10.811

6

C Carbon

12.011

7

N Nitrogen

14.007

8

O Oxygen

15.999

9

F Fluorine

18.998

10

Ne Neon

20.180

3

11

Na Sodium

22.990

12

Mg Magnesium

24.305

13

Al Aluminium

26.982

14

Si Silicon

28.086

15

P Phosphorus

30.974

16

S Sulphur

32.065

17

Cl Chlorine

35.453

18

Ar Argon

39.948

4

19

K Potassium

39.098

20

Ca Calcium

40.078

21

Sc Scandium

44.956

22

Ti Titanium

47.867

23

V Vanadium

50.942

24

Cr Chromium

51.996

25

Mn Manganese

54.938

26

Fe Iron

55.845

27

Co Cobalt

58.933

28

Ni Nickel

58.693

29

Cu Copper

63.546

30

Zn Zinc

65.39

31

Ga Gallium

69.723

32

Ge Germanium

72.61

33

As Arsenic

74.922

34

Se Selenium

78.96

35

Br Bromine

79.904

36

Kr Krypton

83.80

5

37

Rb Rubidium

85.468

38

Sr Strontium

87.62

39

Y Yttrium

88.906

40

Zr Zirconium

91.224

41

Nb Niobium

92.906

42

Mo Molybdenum

95.94

43

Tc Technetium

98.00

44

Ru Ruthenium

101.07

45

Rh Rhodium

102.91

46

Pd Palladium

106.42

47

Ag Silver

107.87

48

Cd cadmium

112.41

49

In Indium

114.82

50

Sn tin

118.71

51

Sb Antimony

121.76

52

Te Tellurium

127.60

53

I Iodine

126.90

54

Xe xenon

131.29

6

55

Cs Caesium

132.91

56

Ba Barium

137.33

5770 Lanthanide

71

Lu Lutetium

174.97

72

Hf Hafnium

178.49

73

Ta Tantalum

180.95

74

W Tungsten

183.84

75

Re Rhenium

186.21

76

Os Osmium

190.23

77

Ir Iridium

192.22

78

Pt Platinum

195.08

79

Au Gold

196.97

80

Hg Mercury

200.59

81

Tl Thallium

204.38

82

Pb Lead

207.2

83

Bi Bismuth

208.98

84

Po Polonium

209

85

At Astatine

210

86

Ra Radon

222

7

87

Fr Francium

223

88

Ra Radium

226

89102 Actinide

103

Lr Lawrencium

262

104

Rf Rutherfordium

261

105

Db Dubnium

262

106

Sg Seaborgium

266

107

Bh Bohrium

264

108

Hs Hassium

269

109

Mt Meltnerium

268

110

Uun Ununnillium

271

111

Uuu Unununium

272

112

Uub Ununbium

277

114

Uuq Ununquadium

44.956

57

La Lanthanum

138.91

58

Ce Cerium

140.12

59

Pr Praseodymium

140.91

60

Nd Neodymium

144.24

61

Pm Promethium

145

62

Sm Samarium

150.36

63

Eu Europium

151.96

64

Gd Gadolinium

157.25

65

Tb Terbium

158.93

66

Dy Dysprosium

162.50

67

Ho Holmium

164.93

68

Er Erbium

167.26

69

Tm Thulium

168.93

70

Yb Ytterbium

173.04 89

Ac Actinium

227

90

Th Thorium

232.04

91

Pa Protactinium

231.04

92

U Uranium

238.03

93

Np Neptunium

237

94

Pu Plutonium

244

95

Am Americium

243

96

Cm Curium

247

97

Bk Berkelium

247

98

Cf Californium

251

99

Es Einsteinium

252

100

Fm Fermium

257

101

Md Mendelevium

258

102

No Nobelium

259

01 atoms molecules stoichiometry - yellowreef · 2013. 9. 16. · (iii) no . answer keys: 2 ......

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