0. common foundation physical q in a level (repaired)

7/24/2019 0. Common Foundation Physical Q in a Level (Repaired)

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Foundation Question of Physical ChemistryStoichiometry (a) Mole

1. The composition of an organic compound W is 54.54% C, 9.09% H and 3.3!%" #$ mass.

i&en that its Mris ''.0, (hat is the mo)ecu)ar formu)a of W*

2. (a) +ene the term relative atomic mass.

(b)The 4 isotopes of )ead occur in the fo))o(ing a#undances-

Relative isotopic mass 204.00!2 20.012 20!.0552 20'.002

% abundance 1.3! 2.3 20.'

51.53

se these data to ca)cu)ate a &a)ue, to 1 decimal place, for theArof )ead.

3. J96 P3 Q3

/hich of the fo))o(ing contains 1 mo) of the stated partic)es*

ch)orine mo)ecu)es in 35.5 g of ch)orine gas

! e)ectrons in 3.01 1023h$drogen mo)ecu)es

C h$drogen ions in 1 dm3of 1 mo) dm3aueous su)furic acid

" o$gen atoms in 22.4 dm3of o$gen gas at s.t.p

#. n a )a#orator$ eercise to determine the degree of h$dration of h$drated

#arium ch)oride, aCl2.xH2", the fo))o(ing resu)ts (ere o#tained-

ass of h$drated #arium ch)oride, aCl2.xH2" 2.44 g6

ass of anh$drous #arium ch)oride, aCl2 2.0' g

se these resu)ts to ca)cu)ate the(

a

)

percentage of (ater of h$dration and 718

(

b

)

correct formu)a of h$drated #arium ch)oride. 728

$. "$gen and h$drogen react ep)osi&e)$ to produce (ater.

(a) /rite a #a)anced euation for the reaction. 718

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(b) miture of 15.0 cm3 o$gen and 55.0 cm3 h$drogen is spar:ed

continuous)$ at r.t.p. ssuming that the reaction goes to

comp)etion,

(i) (hat is the tota) na) &o)ume of the reaction miture at the end ofreaction*

(ii)(hat is the maimum theoretica) decrease in &o)ume*

728

%. 20 cm3of a gaseous h$drocar#on ;CxHy< (as ep)oded (ith an ecess of

o$gen. There (as a contraction in &o)ume of 50 cm3. /hen the products

(ere treated (ith ecess sodium h$droide so)ution, there (as a further

contraction of 0 cm3. )) &o)umes are measured at r.t.p. +educe the

mo)ecu)ar formu)a of .

738

C=

1. The re)ati&e a#undances of the isotopes of a samp)e of neon are sho(n in theta#)e #e)o(.

/hat is the re)ati&e atomic mass of neon in this samp)e* 20.1 ! 20.1! C 20.1' " 20.20 ; occurring #oron*

0.' % ! '.0 % C 20 % " '0 % ; point.

(a) sing the resu)ts of the HCl titration, ca)cu)ate the tota) amount inmo)es of Ea"H in 100 cm3of so)ution +.

(b) sing the resu)ts of the In"4titration, ca)cu)ate the amount in

mo)es of H2"2in 100 cm3of so)ution +.

(c)Hence, ca)cu)ate the amount in mo)es of Ea2" and Ea2"2 formed

during the #urning of the sodium samp)e.

71

8

728

73

8

C=

1. E2"4, a poisonous gas, can #e disposed of safe)$ #$ reaction (ith sodiumh$droide.

E2"4 2Ea"H EaE"3 EaE"2 H2"

/hat &o)ume of 0.5 mo) dm3Ea"H is reuired to dispose of 0.02 mo) of E2"4*

' cm3 ! 12.5 cm3 C 40 cm3 " '0 cm3

2. /hich of the reactions sho(s the greatest change in oidation num#er ofnitrogen*

4EH3 5"24E" H2"! 3E"2 H2" 2HE"3 E"

C 2E" "22E"2" 4EH3 E" 5E2 H2"

3. 2 /P0C Prelim Q2

+isproportionation reaction occurs (hen an e)ement undergoes oidation andreduction simu)taneous)$. /hich of the fo))o(ing euation descri#es adisproportionation reaction* ch)orine in 3Cl" Cl"3

2Cl

! car#on in 2H2C2"42H2" 2C 2C" 2"2C su)fur in 2eB"4 e2"3 B"2 B"3" manganese in 2In"4 n"2 n" I2" 2"2




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#. 2' 00C Prelim Q1Potassium iodate;G< can #e used as a standard in iodine>thiosu)fate titrimetricsince it reacts (ith iodide ions according to the euation-

I"3K;a< 5IK;a< H;a< L 3I2;a< 3H2";land>cross of the fo))o(ing species.

(a)

l2"3 (d)

E"2 (5)

P"Cl3

(b)

l2Cl (e)

E2"4 (h)

B"32

(c)

eCl2 (f) E"2

#.

The ta#)e #e)o( gi&es some information on three ch)orides that ha&e simi)archemica) formu)ae.

Formula ofchloride

shape

(a)

+ra( a dot>and>cross diagram of ,Cl3 U predict the roup to (hiche)ement ,#e)ongs.

(b)

+ra( the stated shapes ofCl3and 4Cl3, and predict the roups to (hiche)ementsU 4#e)ong.

$.

or each pair of su#stances, (hich one has a higher me)tingQ#oi)ing point*Np)ain, in terms of structure and #onding.




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or ;fand>crossV diagrams for a)uminium ch)oride and ammonia.

(b)

Np)ain (h$ these t(o mo)ecu)es form a product (hen the$ react in themo)ar ratio 1-1.

(c)

$ considering the num#er of #onding and non>#onding e)ectron pairs,dra( diagrams to sho( the )i:e)$ shapes of a)uminium ch)oride, ammoniaand the product.

n $our diagrams, c)ear)$ indicate the &a)ues of the #ond ang)es.

&.

(a)

/hi)e su)fur forms the compounds B4and B, no eui&a)ent compoundsof o$gen, "4and ", are :no(n. Buggest (h$ this is so.

(b)

Caesium Duoride has a simi)ar formu)a mass to B.

(i) Btate the t$pe of #onding in these t(o Duorides and suggest a reasonfor the dierence in their #onding.

(ii)

+escri#e and ep)ain three maWor dierences $ou (ou)d epect to ndin the ph$sica) properties of the t(o Duorides.

'.



(a) (i) Btate the t$pe of h$#ridisation for each car#onatom, C1and C2, in the ethanoic acid mo)ecu)e.

(ii) B:etch the shapes of the h$#rid or#ita)s aroundeach atom C1and C2.

(iii) +educe the &a)ue of #ond ang)es a, band c.(b) Car#on atom C2can #e descri#ed as #eing Woined #$

#oth a bondand a bondto one of the " atoms.rieD$ descri#e the terms in italics.

(c) n the &apour state, the Mrof ethanoic acid (as foundto #e 120. Ho(e&er, (hen ethanoic acid (asdisso)&ed in (ater, its Mr(as 0. /ith the aid of a

suita#)e diagram, ep)ain this #eha&iour ehi#ited #$ethanoic acid.

ethanoic acid

Bu#stance

Bu#stance

Bu#stance Bu#stance

(a)

EaCl HCl (5) He Ee

(b) Bi"2 B"2 (h) CCl4 C4

(c)

EaCl g" (i) CH3CH2CH2CH3 ;CH3


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C=

1. /hich of the fo))o(ing pairs of su#stances consists of on)$ giant structures*

a)uminum and si)icon;G< oide! a)uminium oide and a)uminium ch)orideC si)icon and ch)orine" si)icon and si)icon;G< ch)oride

2. Bi)icon car#ide ;car#orundum< is a shin$, hard, chemica))$ inert materia) (ith a&er$ high me)ting point. t can #e used to sharpen :ni&es and ma:e cruci#)es./hich t$pe of structure ep)ains these properties*

giant structure (ith co&a)ent #onds #et(een si)icon and car#on atoms.! giant structure containing meta))ic #onding.C giant )a$er structure (ith co&a)ent #onds #et(een atoms and &an der

/aa)sforces #et(een the )a$ers." simp)e mo)ecu)ar structure (ith co&a)ent #onds #et(een the atoms of

si)icon and car#on.

3. Ho( man$ and #onds are present in the mo)ecu)e on the right*

5 2! 5 3

C 2" ! 1#. compound has the structure as sho(n.

/hat are the &a)ues of the #ond ang)es X, Y,and Z*

> ? @

104.5[ 120[ 10![

! 10![ 1'0[ 104.5[

C 10![ 120[ 104.5[

" 104.5[ 90[ 10![

$. /hich isomer of the h$drocar#on CH14 is )i:e)$ to ha&e the highest #oi)ingpoint*

;CH3


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&. /hich of the fo))o(ing statements cannot #e ep)ained #$ h$drogen#onding*

ce has a densit$ )o(er than (ater at 0o

C.! The #oi)ing point of 2>nitropheno) is )o(er than that of 4>nitropheno).C The #oi)ing point of ethana) is higher than dimeth$) ether, CH3"CH3." The re)ati&e mo)ecu)ar mass of ethanoic acid is 120 (hen disso)&ed in

#en@ene.

/he ;aseous State

1. (a)

Btate the t(o assumptions of the :inetic theor$ of gases that do not app)$for a rea) gas.

(

b)

nder (hat conditions does a rea) gas #eha&e most )i:e an idea) gas*

Np)ain (h$.

2. -#AP3AQ1(c)

Ir$pton reacts (ith Duorine to form a gas Duoride . mass of 0.100 g of occupies 104 cm3 at 2.00104 Pa and 305 I. Ca)cu)ate the re)ati&emo)ecu)ar mass of , and hence suggest its formu)a.

3. -%AP1AQ%)as: ,contains 1 dm3of he)ium at 2 :Pa and Das:contains 2 dm3ofneon at 1 :Pa. f the Das:s are connected at constant temperature and thegases are a))o(ed to mi, (hat is the na) pressure in the Das:s*

#. i&en a ed amount of an idea) gas, s:etch a graph for the fo))o(ing-(a)

pressure ;p< &ersus &o)ume ;G


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(f)

!"

p&ersus pressure ;p


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#.

i&en- *c of C;graphite< 394 :O mo)1, *c of H2;g< 2' :O mo)1.Ca)cu)ate(a)*fof C2H2;g< if *cof C2H2;g< 1300 :O mo)1

(b)*fof C3H!"H;l< if *cof C3H!"H;l< 2010 :O mo)1

(c)*

c

of CH12;l< if

*f

of CH12;l<

152 :O mo)

1

$.

(a)

sing appropriate data in the Data &oo'let, ca)cu)ate the standardentha)p$ change for the fo))o(ing reaction- CH3CH3;g< Cl2;g< CH3CH2Cl;g< HCl;gcata)$sed h$dro)$sis in (ater-

CH3 C"2CH2CH3 H2" CH3C"2H CH3CH2"H

The reaction (as fo))o(ed t(ice (ith dierent concentrations of HCland thefo))o(ing resu)ts (ere o#tained.

Time Qmin

/ith 7HCl8 0.1 mo)dm3, 7eth$)

ethanoate8 Q mo) dm3

/ith 7HCl8 0.2 mo)dm3, 7eth$)

ethanoate8 Q mo) dm30 0.200 0.20025 0.152 0.11550 0.115 0.0!!5 0.0'' 0.03'100 0.0! 0.022125 0.051 0.013

(a) (i) P)ot the graphs on the same aes and sho( that the reaction is rst

order (ith respect to 7ester8. )so, deduce the order of reaction (ithrespect to 7HCl8.

(ii)

+educe the rate euation and ca)cu)ate the rate constant, gi&ing itsunits.

(b) The reaction (as repeated using 0.400 mo) dm3of eth$) ethanoate and0.1 mo) dm3of HCl. Buggest the ha)f>)ife of eth$) ethanoate.

(c) Np)ain, in mo)ecu)ar terms, ho( an increase in temperature can aectthe rate of a reaction.

#.

The rate of remo&a) of the pain>:i))ing drug, paracetamo), from the #od$ is arst order reaction (ith a rate constant, ', of 0.2 hr>1.(a)

Ca)cu)ate the ha)f>)ife of the remo&a) of paracetamo) from the #od$.

(b)

Ho( man$ ha)f>)i&es ha&e passed (hen .25 % of the origina) dose ofparacetamo) remains in the #od$* Hence determine the time ta:en for theorigina) dose of paracetamo) to decrease to this amount.

$. ueous h$drogen peroide decomposes readi)$ in the presence of a cata)$staccording to the euation-

2H2"2;a< 2H2";l< "2;gcata)$sed reaction changes (ithincreasing concentration of the su#strate, and ep)ain the shape of the s:etchat high concentrations of the su#strate.

Blectrochemistry

Part D Blectrolysis1. current of 5.00 is passed through mo)ten copper;< ch)oride for 20.0

minutes #et(een graphite e)ectrodes.(a)

/rite euations for the reactions at cathode and anode.

(b)

Ca)cu)ate the amount of e)ectrons passed through the ce)).

(c)

Ca)cu)ate the mass of copper deposited.

(d)

Ca)cu)ate the &o)ume, measured at s.t.p, of the gas e&o)&ed.

2. The mass of Pt cathode increased #$ 0.30 g after a current of 0.410 hadpassed through di)ute gE"3;a< for '00 s.(a)

/rite euations for the reactions at cathode and anode.

(b)

+etermine the amount of charge passed.

(c)

"#tain a &a)ue of the arada$ constant, , from the a#o&e eperimenta)data.

(d)

Hence, determine a &a)ue of ], the &ogadro constant.

3. 0.!50 g of manganese is deposited on the cathode (hen a current of 1.00 ispassed through a so)ution of manganesecontaining e)ectro)$te for 1.1 hour.(a)

Ca)cu)ate the amount of manganese deposited.

(b)

Ca)cu)ate the amount of e)ectrons passed through the ce)).

(c)

Hence, determine the oidation state of manganese in the e)ectro)$te.




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#. Ce)) 1, containing aueous si)&er nitrate, and Ce)) 2, containing aueouscopper;< su)fate, (ere connected in series. /hen a current (as passedthrough the circuit, 0.10' g of si)&er (as deposited on an e)ectrode in Ce)) 1.(a

)

Ca)cu)ate the amount of e)ectrons passed through the circuit.

(b)

Hence, determine the epected mass of copper deposited at the e)ectrodein Ce)) 2.

(c)

Buggest (h$ the actua) mass of copper deposited is )i:e)$ to #e )ess thanthat in (b).

(d)

Btate ho( the mass of si)&er deposited &aries (ith the fo))o(ing changes-

(i) current is ha)&ed,(ii)

concentration of si)&er nitrate is dou#)ed.

$. n o#Wect (ith a surface area of 1000 cm2is to #e p)ated (ith si)&er of 2 ? 103cm in thic:ness.(a)

+ra( a )a#e))ed diagram of the e)ectrica) circuit for the e)ectro)$sis. n $ourdiagram, inc)ude the po)arit$ of each e)ectrode and the direction ofe)ectron Do(.

(b)

i&en that a current of 5.00 is app)ied, ca)cu)ate the )ength of time, inhours, reuired for the a#o&e e)ectrop)ating to ta:e p)ace. ;+ensit$ of si)&er 10.5 g cm3

0. common foundation physical q in a level (repaired)

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