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School of Chemistry
UNIVERSITY OF KWAZULU-NATAL, WESTVILLE
JUNE 2009 EXAMINATIONS
CHEM 110/CHEM 195: GENERAL PRINCIPLES OF CHEMISTRY
DURATION: 3 HOURS TOTAL MARKS: 100
Moderation Board: Prof J Field Dr M Bala
Dr W van Zyl
University of KwaZulu-Natal
Internal Examiners: Dr P Coombes Ms G Dawson
Prof G Kruger Dr G Maguire
Dr B Moodley Dr Nyamori
Ms L Pillay
IMPORTANT: COMPLETE THIS SECTION IMMEDIATELY
SURNAME AND INITIALS (Optional):___________________________
SIGNATURE: _____________________________________________
Seat
Number:
Student Number:
NOTE: This paper consists of 36 pages, including a periodic table and data sheet. Please
check that you have them all. The use of calculators is permitted. Answer ALL questions on
the question paper and where necessary over the page.
Students are requested, in their own interests, to write legibly.
Question 1 2 3 4 5 6 7 8 9 Total
Internal Marks
External Marks
2School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 2
Section A: Multiple Choice Questions
Answer this section by filling in the correct letter on your MCQ sheet.
1. Oxygen is:
A) a compound.
B) a mixture.
C) an element.
D) always combined with hydrogen. (1)
2. Ethylene glycol has a density of 1.11 g mL-1. What is the volume occupied by
30.0 g of ethylene glycol?
A) 31.1 mL
B) 0.037 mL
C) 30.0 mL
D) 27.0 mL (1)
3. Choose the INCORRECT statement.
A) An anion is a positive ion.
B) A molecule is a group of bonded atoms that exist as an entity.
C) Ionic compounds result from combinations of metals and nonmetals.
D) The molecular formula is the listing of the atoms in an actual
molecule. (1)
3School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 3
Multiple Choice Questions (Continued)
4. Which of the following contains the greatest number of atoms?
A) 1 mole of S8 molecules.
B) 2 moles of P4 molecules.
C) 4 moles of chlorine molecules.
D) All of these contain the same number of atoms. (1)
5. Choose the INCORRECT name/formula combination
A) Sr(IO3)2 strontium iodate
B) NaClO sodium hypochlorite
C) NaClO4 sodium chlorate
D) NaClO2 sodium chlorite (1)
6. Determine the mass percent of H in NH4Cl.
A) 67 %
B) 7.5 %
C) 3.6 %
D) 14 % (1)
4School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 4
Multiple Choice Questions (Continued)
7. What is the formula of sodium bicarbonate?
A) Na2CO3
B) NaHCO3
C) NaCO2
D) NaHSO4 (1)
8. Which of these compounds is insoluble in water?
A) Fe(OH)2
B) MnCl2
C) Ni(NO3)2
D) K2S (1)
9. The oxidation state for the element in the reactant that is oxidised in the equation
below is:
4 Al (s) + 3 O2 (g) → 2 Al2O3 (s)
A) 0
B) - 2
C) + 2
D) + 3 (1)
5School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 5
Multiple Choice Questions (Continued)
10. Identify a neutralization reaction:
A) AgNO3 (aq) + HCl (aq) → AgCl (s) + HNO3 (aq)
B) 2 HI (aq) + H2O2 (aq) → I2 (s) +2H2O (l)
C) NaOH (aq) + HCl (aq) → NaCl (aq) + H2O(l)
D) MgO (s) + H2O (l) → Mg(OH)2 (s) (1)
11. Identify the reducing agent in the following reaction:
NO3- (aq) + S8 (s) → NO2 (g) + SO4
2- (aq)
A) NO3-
B) S8
C) NO2
D) SO42- (1)
12. A light photon of wavelength 500 nm, when compared to light of wavelength
600 nm, has:
A) a higher frequency.
B) lower energy.
C) a greater velocity.
D) a shorter wavelength. (1)
6School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 6
Multiple Choice Questions (Continued)
13. Which electron configuration is impossible?
A) 1s22s
22p
63s
2
B) 1s22s
22p
63s
23p
6
C) 1s22s
22p
62d
2
D) 1s22s
22p
53s
1 (1)
14. A bismuth atom has one more electron than a lead atom. Into which energy sub–
level does this added electron go?
A) 5p
B) 6p
C) 6s
D) 7s (1)
15. The electron configuration of the two outer sublevels of vanadium, element
number 23, is:
A) 3d24s
3
B) 4s24p
3
C) 3d34s
2
D) 3d44s
1 (1)
7School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 7
Multiple Choice Questions (Continued)
16. Which contains both covalent and ionic bonds?
A) NH4NO3
B) BaCl2
C) NF3
D) CH2O (1)
17. How many resonance forms are possible for the Lewis formula of SO2?
A) 3
B) 0
C) 4
D) 2 (1)
18. Which one of the following Lewis structures is INCORRECT?
A) N N
B)
C)
D) (1)
H N O
Be HH
C O
8School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 8
Multiple Choice Questions (Continued)
19. The Lewis dot structure represents one of the resonance
forms of the thiocyanate ion. The formal charges on the N, C and S atoms,
respectively, are:
N C
S
A) - 1, 0, 0
B) + 2, 0, - 1
C) 0, 0, - 1
D) - 2, 0, - 1 (1)
20. Which one of the following molecules is paramagnetic?
A) N2
B) F2
C) NO
D) HF (1)
21. Which one of the following is an exothermic process?
A) Ice melting.
B) Water evaporating.
C) Boiling soup.
D) Condensation of water vapor. (1)
9School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 9
Multiple Choice Questions (Continued)
22. Standard conditions for thermochemistry are,
(a) P = 1 atm
(b) some common temperature, usually 298 K
(c) V = 1 L
A) a only.
B) b only.
C) a and c.
D) a and b. (1)
23. The standard enthalpy formation of NiSO4 (s) at 25 °C is - 872.9 kJ mol-1. The
chemical equation to which this value applies is:
A) ½ Ni (s) + ½ S (s) + ½ O2 (g) → ½ NiSO4 (s)
B) Ni (s) + S (s) + 4 O (g) → NiSO4 (s)
C) Ni (s) + ⅛ S8 (s) + 2 O2 (g) → NiSO4 (s)
D) NiSO4 (s) → Ni (s) + S (s) + 4 O (g) (1)
10School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 10
Multiple Choice Questions (Continued)
24. A pressure of 3.00 atm is the same as a pressure of __________ Torr.
A) 253
B) 33.7
C) 2280
D) 33775 (1)
25. Which one of the following statements about gases is FALSE?
A) Gases are highly compressible.
B) Distances between molecules of gas are very large compared to bond
distances within molecules.
C) Gases expand spontaneously to fill the container they are placed in.
D) All gases are colorless and odorless at room temperature. (1)
26. Which statement about ideal behavior of gases is FALSE?
A) At low densities all gases have similar properties.
B) Gas ideality assumes that there are no interactions between gas particles.
C) All particles in the ideal gas behave independently of each other.
D) Low pressures and high temperatures typically cause deviations from the
ideal gas behavior. (1)
11School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 11
Multiple Choice Questions (Continued)
27. The van der Waals equation for real gases recognizes that,
A) gas particles have non-zero volumes and interact with each other.
B) the non-zero volumes of gas particles effectively decrease the amount of
"empty space" between them.
C) the molecular attractions between particles of gas decreases the pressure
exerted by the gas.
D) all of the above statements are true. (1)
28. When the reversible reaction
N2 (g) + O2 (g) ⇌ 2 NO (g)
has reached a state of equilibrium,
A) no further reaction occurs.
B) the total amounts, in moles, of reactants and products are equal.
C) the concentration of each substance in the system is constant.
D) the product [N2(g)]e × [O2(g)]e = [NO(g)]e2. (1)
12School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 12
Multiple Choice Questions (Continued)
29. Given the reaction:
NO (g) + CO (g) ⇌ ½ N2 (g) + CO2 (g) ΔH = - 374 kJ
The conditions of temperature and pressure that favour the formation of CO2 (g)
are,
A) high T and high P.
B) high T and low P.
C) low T and high P.
D) low T and low P. (1)
30. Given the reaction:
2 NH3 (g) ⇌ N2 (g) + 3 H2 (g) Kc = 230 at 300 °C
which statement most accurately describes the system at equilibrium?
A) More moles of products are present than moles of reactants.
B) More moles of reactants are present than moles of products.
C) Products only are present.
D) Reactants only are present. (1)
13School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 13
Multiple Choice Questions (Continued)
31. The equilibrium constant, Kc, of a system at equilibrium, can be altered by
changing:
A) the catalyst.
B) the effective concentrations of the reactants or products.
C) the pressure.
D) the temperature. (1)
32. In which one of the following gas-phase equilibria would Kp = Kc?
A) H2 (g) + I2 (g) ⇌ 2 HI (g)
B) 4 HCl (g) + O2 (g) ⇌ 2 Cl2 (g) + 2 H2O (g)
C) N2 (g) + 3 H2(g) ⇌ 2 NH3 (g)
D) 2 NO (g) + O2 (g) ⇌ 2 NO2 (g) (1)
14School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 14
Multiple Choice Questions (Continued)
33. Identify the Brǿnsted-Lowry acids and bases in the equation;
NH4+ (aq) + OH- (aq) ⇌ NH3 (aq) + H2O (l)
A) acids NH4+ (aq), OH- (aq); bases NH3 (aq), H2O (l)
B) acids OH- (aq), H2O (l); bases NH3 (aq), NH4+ (aq)
C) acids NH4+ (aq), H2O (l); bases OH- (aq), NH3 (aq)
D) acids NH4+ (aq), NH3 (aq); bases OH- (aq), H2O (l) (1)
15School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 15
Multiple Choice Questions (Continued)
34. Given the following four weak acids:
HF Ka = 6.8 x 10-4
HOCl Ka = 3.8 x 10-8
HNO2 Ka = 4.5 x 10-4
HCN Ka = 4.9 x 10-10
Which is the STRONGEST of these acids?
A) HF
B) HOCl
C) HNO2
D) HCN (1)
[34]
16School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 16
SECTION B: Full Questions
Answer this section on the question paper.
Question 1
1.1 Determine the number of neutrons and electrons in 55Mn2+. (1)
1.2 Naturally occurring chlorine is 75.53 % 35Cl, which has an isotopic mass of 34.969
u, and 24.47 % 37Cl, which has an isotopic mass of 36.966 u. Calculate the
average atomic mass of naturally occurring chlorine (show all the steps of the
calculation). (2)
17School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 17
Question 1 (Continued)
1.3 Calculate the molar mass of sucrose, C12H22O11 (table sugar). (1)
1.4 Calculate the mass, in grams, of 0.433 mol of calcium nitrate [Ca(NO3)2]. The
molar mass of calcium nitrate is 164.1 g mol-1. (1)
[5]
18School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 18
Question 2
2.1 Ascorbic acid (vitamin C) contains 40.92 % C, 4.58 % H, and 54.50 % O by mass.
Calculate the empirical formula of ascorbic acid. (3)
2.2 Balance the following equation by inspection: (1)
NH4NO3 → N2 + O2 + H2O
19School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 19
Question 2 (Continued)
2.3 How many grams of water are produced in the combustion of 1.00 g of glucose
(C6H12O6)? The molar mass of glucose is 180.0 g mol-1. (3)
C6H12O6 (s) + 6 O2 (g) → 6 CO2 (g) + 6 H2O (l)
2.4 Calculate the percentage yield of a reaction that gives a yield of 2.01 g whilst its
theoretical yield is 2.50 g. (1)
2.5 What mass of potassium hydrogen phthalate, KHP, must be dissolved to make
250.0 mL of a 0.1000 M solution? MMKHP = 204.2 g mol-1. (2)
[10]
20School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 20
Question 3
3. The primary standard, potassium permanganate, KMnO4, was used to standardise
a solution of sodium oxalate, Na2C2O4. The balanced REDOX reaction involved is:
2 MnO4- (aq)+5 C2O4
2- (aq)+16 H+ (aq) →2 Mn2+ (aq)+10 CO2 (g)+8 H2O (l)
If 20.00 mL of the sodium oxalate solution required 20.68 mL of a 0.09628 M
KMnO4 solution to reach the endpoint, what is the molarity of the sodium oxalate
solution? Show all your calculations. (3)
[3]
21School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 21
Question 4
4.1 Study the reaction between chromium chloride and sodium hydroxide and answer
the questions that follow.
CrCl3 (aq) + 3 NaOH (aq) → Cr(OH)3 + 3 NaCl
i) Using the rules for solubility, predict the solubility of the products.
(1)
ii) Write the net ionic reaction for this equation. (1)
22School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 22
Question 4 (Continued)
4.2 The following reaction occurs in a basic medium:
Cl2 (g) → ClO- (aq) + Cl- (aq)
Balance the redox equation using the half reaction method. Show your work.
(4)
[6]
23School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 23
Question 5
5.1 The frequency of a spectral line of lithium is 4.47 x 1014 s-1. Calculate the energy
of one photon of this light. (1)
5.2 What is the wavelength of light emitted, in nm, when the electron in a hydrogen
atom undergoes a transition from energy level n = 2 to level n = 1?
(3)
24School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 24
Question 5 (Continued)
5.3 Indicate whether energy is emitted or absorbed when the following electronic
transitions occur: (2)
i) From n = 3 to n = 5
ii) An electron adds to a H+ ion and ends up in the n = 1 energy level.
5.4 If the orbital angular quantum number is l = 3, what are the possible ml values?
(1)
25School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 25
Question 5 (Continued)
5.5 How many orbitals are there in each of the following sub-levels?
(1)
i) 3d
ii) 4f
5.6 For each of the following write the condensed electronic configuration:
(2)
i) Rb
ii) Bi
[10]
26School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 26
Question 6
6.1 Draw Lewis dot structures for the following compounds.
i) KCl (1)
ii) C2H4 (2)
6.2 Use Lewis structures and formal charges to draw stable resonance structures
for [NO3]¯. (3)
27School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 27
Question 6 (Continued)
6.3 i) Draw three plausible Lewis structures representing the polyatomic anion,
CNS-, with nitrogen as the central atom. (3)
ii) Decide, on the basis of the formal charges, which one of the structures is the
most plausible. (1)
28School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 28
H
C
Question 6 (Continued)
HH H H
6.4 The drawn compounds are shown in order of increasing boiling point from (a) to
(d): H
HH
OH
H
CH
O HC
OH
C
H
CHH C H H
HH
(a) (b) (c) (d)
Lowest Highest
Explain fully the above order of boiling points. (4)
[14]
29School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 29
Question 7
7.1 A quantity of 200.0 mL of 0.862 M HCl is mixed with 200.0 mL of 0.862 M KOH in
a constant-pressure calorimeter of negligible heat capacity. The initial
temperature of HCl and KOH solutions is the same at 20.48 °C.
For the process,
H+ (aq) + OH- (aq) → H2O (l)
the heat of neutralization is – 56.2 kJ mol-1.
What is the final temperature of the mixed solution? (Note: The density and
specific heat capacity of the solution are 1.00 g mL-1 and 4.18 J g-1 °C-1
respectively). (4)
30School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 30
Question 7 (continued)
7.2. For the following combustion reaction,
C3H6O (l) + 4 O2 (g) → 3 CO2 (g) + 3 H2O (l) ∆H° = - 1790 kJ mol-1
Calculate the enthalpy of formation (∆H°f) of acetone (C3H6O) using the following
information: the enthalpies of formation for CO2 (g) is - 393.5 kJ mol-1 and for
water is - 285.8 kJ mol-1. (2)
[6]
31School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 31
Question 8
8.1 i) What is the density, in g L-1, of a sample of Cl2 gas at 1124 Torr and
24.0 °C? (Note: The molar mass of Cl2 is 70.90 g mol-1).
(2)
ii) What is the mass of Cl2, in grams, if the volume is 9.22 L? (1)
32School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 32
Question 8 (Continued)
8.2 Ammonium sulfate is prepared by reacting ammonia with sulfuric acid as shown in
the following reaction,
2 NH3 (g) + H2SO4 (aq) → (NH4)2SO4 (aq)
if 1774 moles of NH3 reacts with sulphuric acid at 315.15 K and under 15.6 atm,
calculate the volume of ammonia required for this reaction in litres. (1)
[4]
33School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 33
Question 9
9.1 For the reaction,
CO (g) + 3 H2 (g) ⇌ H2O (g) + CH4 (g) KC = 190 at 1000 K
if the initial concentrations are [CO (g)] = 0.025 M, [H2 (g)] = 0.045 M, [H2O (g)]
= 0.025 M, and [CH4 (g)] = 0.046 M:
i) Calculate the reaction quotient, Qc, for this reaction. (1)
ii) In which direction will the system move to attain equilibrium? (1)
9.2 Calculate the pOH of a 7.0 x 10-3 M aqueous solution of Ca(OH)2 at 25.0 °C,
assuming complete dissociation. (1)
34School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 34
Question 9 (Continued)
9.3 What is the [H3O+]e of a solution of formic acid with an initial concentration
0.250 M? Ka = 1.8 x 10-4.
(5)
[8]
35School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 35
36School of Chemistry, University of KwaZulu-Natal, Westville campus
CHEM 110W/CHEM 195: General Principles of Chemistry
June 2009 Examination
Page 36
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