Enne Retics Ans

8/10/2019 Enne Retics Ans

1/122

1. D[1]

2. (a)

(1)for around carbon and its hydrogens

(1)for around oxygen and its hydrogen

Allow all dots or all crosses

Ignore circles around atoms 2

(b) (i) C(s) / (graphite) + 22(g) + 2!2(g) Correct species (1)

Allow oxygen abo"e arrows rather than in box

#alancing and state symbols (1)

$econd mar% dependent on correct species except as below with

either hydrogen or oxygen or both as atoms

e&g

C(s) / (graphite) + '(g) + '!(g)

$cores second mar% 2

(ii) nthalpy / energy / heat(energy) change when one mole of a

substance (1)

Is formed from its elements (in their most stable / standard states) (1)

nder standard conditions of 2*,/ 2- .C / any statedtemperature

AND atm pressure / 0 %1a / 00 %1a (1)

Definitions based on lattice enthalpies may score third mar% only

heat required / heat given out / heat taken in

(iii) 3

c4 53

+ 32

(1)

4 (2 6 72-& + 7*&-) 8 (72*&)

4 792: (1)

Ignore units

Correct answer alone 4 2 mar%s

+92: 4

5''0&2 4 if omit multiply by 2 2

1


2/122

(c) (i) 20&9 6 200 6 '& 4 90-(&2) (;) ignore sf except sf i&e& 20000

OR

20&9 6 200 6 0&00' 4 9&0-(2)%;

ignore sf except sf i&e& 20

ignore signs

ignore mol7

(ii) 0&'/2 4 0&02:- (mol)

ignore sf except sf i&e& 0&0

(iii) 90-&2/0&02:- 4 7:-000 (; mol7

) (sf)

OR

7:- (%; mol7) (sf)

Ignore missing units but penalise incorrect units

Allow


3/122

4. (a) (i) 3S

system4 0*&2 + (:6 :*&*) 7 ' (1)

4 (+)-&:(; mol7

,7

) / (+): (; mol7

,7

) (1)

OR

(+) 0&: (%; mol7,7) (2)

I@!B units e"en if incorrect

correct answer with no wor%ing scores 2

alue using for 2! 4 7:&* scores

se of "alue for 2!(g) (&9) gi"es

*&' (; mol7

,7

) (1)

correct "alue with incorrect sign scores 2

185

(ii) es as (solid and) liEuid forms (from solid) / number of moles

increases

OR

If 3S

systemin (i) is negati"e the sign is not as expected as liEuid

forms from solid / number of moles increases

Disorder increases, with no ref to liquid or numer of moles

(iii) First mark

3$

surroundings4 2*+

)000(&++7

(1)

Second mark

4 72*-&:9-

4 72*-&: ; mol7

,7

(1)

correct units must be shown but order not important

OR

70&2*-: %; mol7

,7

(1)

correct units must be shown but order not important

correct answer with or without wor%ing and correct units scores (2)

ignore sf except

correct "alue with positi"e sign scores 2

3


4/122

(i") (-&:72*-&:)

4 7110 (J mol1

1

)

!B

70.110 (kJ mol1

1

)

could use : or 2*: etc


5/122


6/122

(d) ,-

First mark

irdioniNation energy i(er)for Gg / Gg 4 99 %; mol7

(third

ioniNation energy for Co 4 22 %; mol7

) (1)

Second mark(


7/122

(c) (i) Goles acid 4 ((2- 6 2/ 000)) 4 0&0-/0&0-0 / - 6 072

Ignore units and sf

(ii) Gass Gg C!4 ((0&0- 6 '& R 2)) 4 2&09-/ 2&0 /2&/2& (g)

AMM!P


8/122

(") 00F yield 4 (20& 6 0&02-) /-&0(2-)g) (1)

yield 4

)00

0+&-

9-&(

4 4F (1)

!B

Gol magnesium chloride 4)&20

9-&(

4 0&0''-/0&0'-/0&0'/0&0 (1)

yield 4 02-&0

)0+'-&000(

4 4F (1)

$econd mar% can be gi"en as


9/122

(ii) TPC

I7

larger (than Cl5) (1)

so (ion) easier to polarise /distort (1)

AMM!P for 2nd

mar%

increases co"alent character / more co"alent than GgCl2/ con"erse

for GgCl2/ description of polarisation instead of the term

If clearly ions allow reference to iodine instead of iodide (Kiodine

has a larger ionL)

Bead in conUunction with (i)& Direct comparison not needed if (i)

co"ers bonding in chloride& 2

Si=e of atoms rather than ions #is larger than l

#molecules are polarised 4g>

is polarised

#odine more electronegative than chlorine

(e) (i)

)20

0

00(:

4 2 6 07

(g)

AMM!P 0&002(g)

/-00 (g)

2 6 07:

%g

I@!B F as unit

? 1;7

@ ;9;;;

(ii) (Gore) soluble (in water)/ (more) soluble in blood stream/ can be gi"en

as solution/ won?t produce gas in stomach / won?t react with stomach

acid/ doesn?t produce C!2Con"erse answers for GgC!!r other "alid answers

AMM!P can be gi"en in liEuid form

4glis a liquid

4g&Ais too reactive

[16]

9


10/122

#. (a) Allow formulae throughout instead of names

estH add bromine (water) /bromine solution AMM!P bromine gas

/bromination (1)

Res&ltH no change with hexane / stays orange brown/ stays red brown/ stays

yellow and

goes colourless with hex55ene(1)2ndmar% cE on st

!B

estH add (acidified) potassium manganate((II)) (solution) (1)

AMM!P potassium permanganate for potassium manganate(II)

Res&ltH no change with hexane/stays purple

and

goes colourless / brown with hex55ene (1)

!B

est 5add al%aline potassium manganate((II)) (solution) (1)

AMM!P potassium permanganate for potassium manganate(II)

Res&lt5no change with hexane/stays purpleVand

goes green with hex55ene (1) 2

Smokiness of flame

Bromide

#odine

$oes clear

(b) (i)

AMM!P 1artially or fully displayed as long as the two are trans

Allow bonds which go closer to the than to C of al%yl

groups on l&h&s&

(ii) TPC

C4C restricts rotation/ C4C pre"ents twisting /C4C can?t rotate/ lac%

of free rotation round C4C (so the groups can?t change position

relati"e to the bond) (1)

ex725ene has different groups on the C at each end of C4C /

hex55ene has 2 hydrogens on the C at one end of C4C / hex55ene

doesn?t ha"e different groups on the C at one end of C4C / hex55ene

has no group which ta%es priority on the C at one end of C4C (1)

(answer can be considered from either hex 75 ene or hex525ene) 2

!lkenes can*t rotate Doule ond is fied Bonds can*t rotate

Doule ond is on first caron 3unless further eplanation6

10


11/122

(c) (i) ignore signs

(-0 6 ': 6 '&) 4 *:'(;)/ *&:' %; (if con"erted to %;

units must be stated)

AMM!P *:0 / *:00 /*&: %; /*&: %;

35;9A ? C ? C9186 @ E:3"6

(ii) !ne mar% each for moles of hexane energy change sign units

2 sig figs (for energy change calculated)

Goles hexane 4 0.326#"4 (&92 6 07

) (1)

(*:'/ &92 6 07

) 4 2-'000 ;/ 2-' %; (1)

H7 82"00 kJ mol1

/52 :00 000 ; mol7

/ 52&:60:; mol

7(1)

Allow


12/122

(i") rror in reading temperature is less than the effect of ignoring heat

loss etc

AMM!P

!ther errors are greater than error in temperature reading / Beadings

are within margins of error/


13/122

(iii) $ame (number and type of) bonds are bro%en and made in each reaction

/ one C4C (and one 5) are bro%en and two C5 made

AMM!P

reaction is 7C4C5 + 2O 5C25C25 each time

($imilar energy change) as in each case 2reacts with C4C

!ll are alkenes going to alkanes

all have the same doule ond which reacts in the same way[17]

+. C[1]

10. C[1]

11. A[1]

13


14/122

12. (a) (i)

/ner9 cane :etter;'6kJ

mol1

Mattice energyfor sodium

chloride

/ 599-

nthalpy change

of atomiNation

of sodium

+0*

nthalpy change

of atomiNation

of chlorine

A +2

Jirst ioniNation

energy ofsodium +'*'

Jirst electron

affinity of

chlorine

F

nthalpy change

of formation of

sodium chloride

D 5'

: correct letters (3)

- or ' correct letters (2)

or 2 correct letters (1) or 0 correct letters (0)

(ii) xpression such asH

D 4 C + # + A + J +

5 ' 4 + 0* + '*' + 2 + J + (7 99-)

J 4 7 ' 7 0* 7 '*' 7 2 + 99- (1)

AnswerH

J 4 7:0 (%; mol7

) (1)

heck empty o in 3a63i6, as

answer may e written there9

Answer must follow from wor%ing

Correct answer only (2)

Correct answer with some consistent wor%ing (2) 2

14


15/122

(b) (i) (#onding in aCl) 00F ionic

OR

almost completely ionic

OR

no co"alent character/("ery) little co"alent character

)4olecule* (0)

(ii) ,-

AgI has (a degree of) co"alent character (1)

due to polariNation or distortion (of the anion) (1) 2

(c) ,-

Any toof the followingH

W (outermost) electron further from the nucleus/atoms get

bigger/more shells

W (outermost) electron more shielded (by inner shells of e5)

W (force of) attraction between nucleus and (outermost)

electron decreases (down the @roup) OR(outermost)

electron held less strongly (down the @roup) OR(outermost)

electron becomes easier to remo"e (down the @roup)

#$%&'(any references to(effecti"e) nuclear charge or more protons& 2

ionsget igger 3down $roup6[10]

13. (a) (i) -+

*0&2

4 0&0-(00) (mol)

correct answer only (1)

(ii) 200 6 '& 6 *#.2

4 ':-- (;) OR'&:-- %; (1)

for correct 32(1)

#$%&'(sf

#$%&'(signs at this stage 2

15


16/122


17/122

(c) (i) nthalpy / energy / heat (energy) change

(when)

one mole of a substance/one mole of a compound (1)

is formed from its elements (in their most stable states) (1)

2*, / 2-.C / a stated temperature AND atm pressure/00 %1a (1)#$%&'(any references to concentration

7energy required

OR

7energy released

7one mole ofproduct(s)

is formed from its reactants

room temperature/rtp

(ii) Cycle or formula expression

30Zf4 307 302

4 (2 6 7 *') + (2 6 7 2:) 7 (7 90)

44+0(%; mol7)

W correct expression or cycle (1)

W e"idence for doubling >ot

3ZcXCY and30

ZcX2Y (1)

W answer (1)

Correct answer with no wor%ing scores full mar%s [15]

14. #[1]

1*. C[1]

17


18/122

1". D[1]

1. (a) D

(b) C

(c) A [3]

1#. D [1]

1+. (a) (:&02 6 02

6 2'

-0

)4

&2- 6 02'

/ &2-' 6 02'

/ &2: 6 02'

Allow


19/122

20. (a) (i) ''0

(ii) 0&0-

(iii) (7'&'/ 0&0-) 4 7 2*' %; mol7

alue (1)

egati"e sign and units (1)


20/122

(b) 0f4 0a(Cu)+ m(Cu)+ m2(Cu)+ 2 6 0a(/2 #r2)+ 2 6 aff(#r)+ 0latt!B

Mattice energy 4 D7(other enthalpy changes) (1)

Can be shown using the numbers

4 7'& 7 (& + 9': + *- + 2 6 &* + 2 6 7'2&:) 4 7'& 7 2-0&*

4 72922&9 4 7292 (%; mol7

) (2)

max if no multiples of 2 for #r

max 2 (out of ) if positi"e sign

(c) (i) TPC

ot 00 F ionic/ has some co"alent character

'eject answers where it is not clear that onding has some

intermediate character, ut not entirely ionic or covalent

(ii) on5spherical bromide / negati"e ion with bulge towards

copper / positi"e ion (1) [8]

22. (a) Initially Cu$!'in excess so amount of reaction depends on amount of \n

or

Gore Cu$!'reacts (as more \n added) (1)

!ccept uS&Cin ecess!ccept more Gn reacts

'eject reaction is eothermic

@raph le"els off because all Cu$!'used up (1) 2

!ccept Gn now in ecess

'eject just )'eaction is complete*

(b) (i) eat capacity (of metal)

low (compared with that of solution)

!ccept metal has negligile/low specific heat capacity

!ccept metal asors 3much6 less heat 3than solution/water6

(ii) E 4 -0 6 :&- 6 '& 4 29&- ;

nits if gi"en must be correct

Ignore signs

!ccept 1AA;;/1A:;/1A:

!ccept answer in k" only if units stated

'eject 1A:1

20


21/122

(iii) Goles Cu$!'4 -0 6 000

2-&

4 0&0:2- (1)

orrect answer with some working scores full marks

!ccept (cf from moles

0 4 (7) 0000:2-&0

-&29

(1)

4 7 22 (%; mol7

)

mar% for negati"e sign

mar% for answer to $J

nits if gi"en must be correct '

!ccept (cf from 3ii6 gives H1A/H1/H1

(c) (i) xtra precision negligible compared withapproximations in calculations/heat loss

!ccept measuring cylinder is least accurate measuring

instrument

(ii) se a lid on the cup (to reduce heat loss)

!ccept etra insulation for cup

!ccept weigh uS&Csolution

!ccept use urette/pipette to measure volumes

'eject repeat eperiments&'

use more accurate alance

&'

Smaller mass intervals[10]

23. (a) O@ A

Ag3g6 (1)

O@ J3g6 (1)

H enthalpy (change) of formation (of!gI )/]0f/]0formation(1)

I@!B reference to >standard?

!ccept )heat of formation*

21


22/122

(b) (i) /'/R

'eference to 7atoms or 7molecules or 7I or 7# scores

(0) overall

FRS AR5

/'/R

iodide (ion) larger than fluoride (ion)

!cceptjust iodide has smaller charge density than fluoride*

scores first mark

OR

$um of ionic radii in AgI larger (than in AgJ)

!gJK scores (0) overall

OR

halide ion or 7or anion increases in siNe down group (1)

!ccept 7atomic radius of halide ion/KH

/anion increases 3down

group6

S/OND AR5

Charges (on anions) same (1)

'RD AR5

(so) wea%er (forces of) attractionbetween ions (in AgI) (1)

!ccept 7weaker ionic onding (1)

'ejectjust 7weaker onding 3in !g#6

&''(2 '(L('S( !'$+4(%2S !% S&'( !-- 20( 4!'MS

OR

First and second com>ined >9 statin

I7

(ion) larger than J7

(2)

!cceptjust iodide has smaller charge density than fluoride

scores only one mark

'RD AR5(so) wea%er (forces of) attractionbetween ions (in AgI) (1)

!ccept 7weaker ionic onding (1)

'ejectjust 7weaker onding 3in !g#6

!"OR# $"% R#R#"'# O *O+$R$O" O&

O" $"%,H#R# " (-)(i)

22


23/122

(ii) 1 scores (0)

(ii) !gI soluble /!gI slightly soluble (1)

#f >1 3k" molH1

6 in 3i6, !gI insolule (1)

as ]$!Mexothermic / negati"e (1)

!ccept ecause endothermic / positive (1)

4!'M #%D((%D(%2-N

Gar% CT on sign and magnitude of answer in (i) 2[4]

23


24/122


25/122

(c) (i) Gultiplies the ,C!eEuation by 2 (1)

and subtracts the ,2C!eEuation from it (1)


26/122

(d) First mark5

cis smaller as $orard reaction is endotermic (1)

(quilirium moves to left and so allsscores 3;6

Second mark5

eca&se of a change inMc&

Increases the amount of ,C!/reactants

!B

decreases amount ,2C!/products (1).

IfMcis said to be larger then the second mar% can be awarded

conseEuentially for saying that the amount of ,C!decreases etc& 2

!ccept equilirium shifts to the left

'eject more M0&Athan M&A[10]

2". (i) $ (s) + !2(g) + 22(g)

correct entities (1)

state symbols and balancing (1) 2

(ii) nergy change when mole of a compound is formed (1)

from its elements (in their standard states) (1)

at 2*,/Euoted temperature and atm (1)

(iii) (2 6 72-&) 7 (72*:& +(2 6 720&:)) (1)

4 72&:/72' (%; mol7) (1)

Allow transferred error for one minor slip (e&g& 20&' instead of 20&:)

but not for omission of multiples&

Ignore units 2

'eject HAA

'eject HA;[7]

26


27/122

2. (a) /2goes from 0 to 7 4 reduction (1)

/2goes from 0 to (+) 4 oxidation (1) 2

#f 7the oidation numer of % goes down hence reduced and the

oidation numer of 0 goes up and hence oidised 32a3 16

#f all &9%9 correct ut fails to state which is oidation andwhich is reduction scores 19

#f all &9%9 correct ut oth reactions misclassified, scores =ero9

!ny answer not referring to nitrogen or hydrogen scores =ero9

(b) (i) Calculation of bonds bro%en ': 6 + *''/ (4 22-2) (1)

Calculation of bonds made 6:/ (4 22) (1)

]0 4 79: (%; mol7

) (1)

mar% conseEuential on numerical "alues calculated abo"e

orrect answer with some working scores A marks

orrect answer alone scores marks

(ii) A"erage / mean bond enthalpy used for N' >ond 6 ammonia

'eject just 7average ond enthalpies used

(iii)


28/122

(c) (i) TPC

!ne way

temperature increase therefore molecules ha"e greater (a"erage

%inetic) energy (1)

!ccept moving faster

more molecules/collisions ha"e act(1)


29/122

2#. (a) (i) Gass 4 2- + 22&9- 4 '9&9- (1)or in eEuation below

'9&9- 6 '& 6 0&- 4 20*: (;) (1)

(4200 (;))

conseEuential on calculated mass 2

!ccept correct answer with some working (/)

+se of incorrect mass 3e9g9 m @ 1 g6 can gain ndmark

!ccept answer changed to k"

(ii) Goles (water)4 000

-&2-

4 0&09- (1)

4)09-&000(

20*:)(

(1)

77--&* (%; mol7

) (1)

both "alue in %; mol7 and sign needed

Xignore $JY

!ccept correct answer H559E or H59; k" molH1

with some

working 3A6

0 @9;A:5631;;;

1;;63

(1)

4H59; 3k" molH1

6 (1)

scores full marks

onversion to k" can e at final stage

(b) Any one of o heat is lost (to the surroundings)

!B

1olystyrene cup or thermometer ha"e negligible heat capacity

!B

All the acid was transferred (from the bea%er) to the polystyrene cup

!ccept takes up negligile heat[6]

2+. (a) (i) ]0:

(ii)-

-

2

!B

20

0

'eject 05

29


30/122

(b) ither

]0f @ ]02> ]0> ]0'> ]0-> ]0:

!B

]0f 4 (+9) + (9-) + 2 6 (+2) + 2 6 (79) + (72*)

4 7: (%; mol7) (1)

Correct answer with no wor%ing (2)

#gnore k" 2

Iirst mark only if doules oth P0atand electron affinity for

hydrogenT

nd mark is only consequential on failure to multiply either

P0ator electron affinity or oth givingU JC;C / J11A /JAA1

3k" molH1

6T

>18 scores (0)

>C;C / >11A />AA1 scores (0)

30


31/122

(c) /'/R

First mark5

Gagnesium/Gg ion smaller (radius) than calcium/Ca ion

!r

the sum of the ionic radii in Gg2smaller (than in Ca2) (1)

!ccept magnesium ion has greater charge density than calcium

ion for first mark9

'eject reference to )atoms* or )molecules* or )0* scores =ero

o5erall9

Second mark5

but charges the same (1)

ird mark5

(so) stronger (forces of) attractionbetween ions (in4g02) (1)

XCorrect re"erse arguments can score both mar%sY

!ccept 7stronger ionic onding for Ardmark in either case9

#f 70>ions or 7hydrogen ions referred to, A

rdmark cannot

e awarded in either case

#f just 7stronger onding in 4g0, Ard

mark cannot e

awarded in either case

OR

First and second mark com>ined5

4g2+

(ion) or4g2+

(cation) smaller (radius) than a2+

(2)

ird mark5

(so) stronger (forces of) attractionbetween ions (in4g02) (1)

XCorrect re"erse arguments can score both mar%sY

Ignore references to polarisation of the hydride ion or Kco"alent

characterL in the hydrides&

Ignore references to Kenergy reEuired to separate ions/brea% bondsL [7]

30. (a) Gg(s) + C(graphite) + !2(g) in both left hand boxes#alancing (1)

state symbols for Gg/C/!2must be present and correct at least once (1) 2

!ccept 3s6

!ccept everything in all oes douled 3allow 0l rather than

C0l6

'eject equation with & or &in it

31


32/122

(b) (i) 02'

&0

4 '&9 6 07

/ 0&00'9

!ccept ;9;;C1 3recurring6

!ccept ;9;;C

'eject ;9;;C'eject ;9;;C1

(ii) Goles of Cl at the start 4 0&2 (1)

Goles of Cl reacted 4 2 6 0&00'9

4 0&00' (1)

Goles of Cl left 4 0&2 7 0&00'

4 0&*:: (1)

ignore sf

!ccept transferred error from 363i6

(g ;91E

;91E1:

'eject ;9

!ccept ;91E

3forgetting to multiply y 6

.orth ma of

(ii) Axes labelled and suitable scale 7 must co"er more than half

the pro"ided grid and time must be on the horiNontal axis (1)

All points plotted accurately and suitable cur"e/straight lines (1)Jrom 0 to minute must be straight horiNontal line&

Jrom to 2 minutes "ertical or sloping line to 2-& or

abo"e& Jrom 2 to : minutes straight line or smooth cur"e& 2

'eject temperature scale starting at ;F 31 ma6

(i") nergy change 4 '&2 6 00 6 '&-

4 &* (%;)

!ccept 18E; 3"6

!ccept 19E 3k"6

!ccept 1E;; 3"6!ccept with either > or H or no sign

'eject answers using mass @ 1;;91g

$iving 18E198E 3"6

'eject " molH1

k" molH1

32


33/122

(") 4 00'9&0

+*&

4 7'- %; mol7

(2)

mar% for number and for sign and units 2

!ccept 2( from 363i6 and 3iv6

Second mark dependent on the first

("i) ither lines drawn on graph to show maximum temperature

rise should be '&-

!r

$ome heat loss (and so the reading of '& was too small)

!ccept ma temperature etween 1 and minutes

'eject rounded up to nearest ;95

(c) (i) 2' + 2 + x : 4 ' (g) (1)

umber of moles 4 2&2/' 4 0&02:2 / 0&02:* (1)

Ignore sf except if only (i&e& 0&0) 2

!ccept ;9;

'eject ;9;1

'eject ;9;

(ii) ] 4 02:2&0

0-&

4 7 '0& %; mol7

!ccept correct sign and units needed for mark

!llow M instead of k HC;91A1

!llow 2( from 3c63i6

'eject C;91

(d) ]f4 ]+ ]27 ](1)

4 7 '- 7 :0 + '0

4 7 0*0 %; mol7(1) 2

&nly penalise missing units once

!ccept H1;EA

!ccept transferred errorU

P01@ 363v6

P0@ H8;

P0A@ 3c63ii6

correct answer with no working gets marks

'eject incorrect application of 0ess*s -aw (0)

33


34/122

(e) lements don?t react together to form magnesium carbonate

'eject hard to measure temperature of solid[18]

31. '--&: + ' 6 2&9 (' 6 '09&')

Gultiples (1)

ess applied (1)

4 7:9(&2) %; mol7

(1)

ignore sig fig

In general deduct one mar% for each mista%e

!ne wrong or missing multiples (2max)

ess the wrong way round (2max)

o sign with answer (2max)

xamplesH +:*&* (no multiples at all is two errors) (1)

70-2&/+-- (either multiple missing) (2)7*0&: (2 6 Cl atomisation) (2)

+:9&2 (ess misapplied) (2)

+0-2&/7--/+*0&: (1)

7:*&* (0)[3]

32. (a) Correct answer 9& with some wor%ing (2)

!ccept :A9;5 g / :A9; g / :A g


35/122

(b) TPC

C + 2 C l

a

' 2

C + ' C l

C'+ (2)Cl2and C + (')Cl at correct le"els (1)

] correct / 72* (1)

acti"ation energy hump (does not need to be labelled) (1)

!ccept

o r

doule headed arrow

'eject activation energy hump shown as straight lines

'eactants and products

HP0

xplanationH

Beaction/it has a i acti"ation energy (1)

I@!B reactants/methane and chlorine are %inetically stable

in combination with high acti"ation energy

u" pro"ides energy to brea% Cl7Cl bonds (1)

!B

Cl radicals are produced in the presence of u"

'eject +L provides the reactants with energy to overcome the

(a

I@!B any references to thermodynamic stability -[7]

35


36/122

33. (a) TPC

enthalpy / energy / heat change when mol of a substance (1)

!ccept heat / energy / enthalpy released

!ccept oth 7element and compound instead of sustance

'eject energy etc required'eject 7reactant instead of sustance

is burnt in excess/burns completely in air6oC9en (1)

!ccept complete comustion with air/oygen

&' reacts completely with air/oygen

'eject reacts with oygen

conditions of atm/ 00 %1a/0 %1a pressure and

specified temperature/2* , (1)

'eject room temperature

(b) (i) #ottom box

2C!2(g) + 2!(l)

balance and state symbols (1)

Meft arrow label

P0c + AP0c0!B (2x 7 *') + (x 7 2:) (%;) units not essential

!B 797-

!B 7:': %; (1)

right arrow label

]cC2-!

!B 79 (%;) (1)

(ii) ]fC2-! 4 (2x 7 *') + (x 7 2:) 7 (79) (1)

4 729- (%; mol7

) (1)

!B

mar% for teir left hand arrow minus teir right hand arrow

for correct conseEuential sign and answer 2

.rong unit negates last mark 3ut allow k"6

[8]

36


37/122

34. (a) In (a)(i) (ii) and (iii) penalise $J on the first occasion only&

ACC1< 2$J

(i) Gass methanol burnt 4 0&' (g) (1)

2

'&0

4 0&00: (1) 2

!ccept ;9;11, ;9;1;A, ;9;1;5

V on incorrect calculation of mass

orrect answer with some working (/)

(ii) ot re&ired

orrect answer with some working (/)

If the final answer is incorrect the 2nd mar% is only

accessible if energy is di"ided by moles in first part of calculation 2

(b) (i) -&2

0&

6 00 4 ()'&:- F

I@!B $J

37


38/122

(ii) (2&- + &0 4) 22&- (.C)

!B

('' 7 2&-)422&- (.C)

!B

00:-&0'

-&2 4 22&- (.C)

CT on F error in b(i) if this is used to calculate the temperature

'eject all other values

(c) (i) "aporation (of methanol/alcohol)

!ccept turns to vapour

&' methanol volatile

'eject alance faulty or spills or 4ethanol reacts

(ii) Carbon (1)

Mower/less exothermic (1) ignore references to incomplete

combustion 2

!ccept soot

'eject any other sustance[11]

3*. (a) (i) Gg2+

(g) (+) !27

(g)

'eject if state symols missing

'eject if eH

included in o

(ii) ]0(nthalpy of) formation (of Gg!) (1)

]02(nthalpy of) atomisation (of Gg) (1)

]0stplus 2

ndelectron affinity (of !)

!B stand 2ndelectron affinity (of !) (1)

!ccept recognisale areviation such as 7(! for electron

affinity9

38


39/122

(iii) ]0f4 7:02 4 (+-0) + (+2:) + (+2'*) + (+:-9) +-(

!B

(M 4) 7(+:-9)7(+2'*)7(+2:)7(+-0)+(7:02)(1)

Douling electron affinity and/or atomisation values scores (0)

(M 4) 7'' (%; mol7) (1)

Correct answer only with no wor%ing (1 maC) 2

'eject any incorrect sign in algeraic epression (0)

(b) (i)

6 polarises 3#H

ion6

!ccept 7distortion if clearly linked to the iodide ion

!ccept 74g ion

!ccept 7# ion &' 7iodine ion

'eject any reference to atoms or molecules

e9g9 74g polarisesW99

'eject 7iodine/#/#is polarised

'eject wrong polarisation e9g9

7magnesium ion is polarised

7#H

polarises 4g>

(ii) Badius/siNe (of ions) (1)

!ccept distance etween ions&' Sum of 3ionic6 radii

&' 2ype of crystal structure

&' 4adelung constant

'eject 7ato2ic radius

charge (on ions) (1) 2

!ccept 7harge density

39


40/122

(iii) Mess (exothermic) (1)

!ccept Smaller

&' more endothermic

&' -ess negative

&' -ower

'eject higher/greater

co"alent character (strengthens lattice) (1)

!ccept theoretical value ased on purely/1;; X ionic model

'eject any implication of magnesium iodide eing totally

covalent

Gar% each aspect independently 2[11]

3". (i) nthalpy change when mol of gaseous ions (1)

!ccept energy or heat

'eject any implication of an endothermic process

e9g9 energy required

'eject 7W91 mol of gaseous ato2s

is dissol"ed such that further dilution causes no

further heat change (1)

!ccept 7added to water/reacts with water instead of

7dissolved

'eject just 7hydrated

'eject just 7completely hydrated

I@!B Kstandard conditionsL

!ccept is dissolved to form an infinitely dilute solution

&'

#s dissolved in a large/ecess/infinite amount of water

ark eac as=ect inde=endentl9 2

40


41/122

(ii) /'/R

]0S&-%4 (7]0-(+ ]00ND) (1)

xpression Euoted or correctly used in at least one of

the calculations below

!ccept answer only with no working (1)

]0S&-%4gS&'4 7(729') + (7*20)

4 +*-' (%; mol7

)(1)

]0S&-%4BaS&'4 7(729') + (7:0)

4 +0' (%; mol7

)(1)

!ccept answer only with no working (1)

nthalpy of solution of Gg$!' less endothermic/more

exothermic/more negati"e than for #a$!' so Gg$!'more soluble than #a$!' (or re"erse argument) (1)

'ejectjust 7soluility/P0solndepends on a alance etween

lattice and hydration energies

OR

(both) lattice energies and hydration enthalpies

decrease from Gg$!'to #a$!'(or down group) (1)

!ccept 72he hydration energies decrease fasterW99

'eject 3H65;; and 3H65; stated without further eplanation

(but) lattice energies change less (1)

]0S&-%4 (7]0-(+ ]00ND) (1) stated in words or symbols

'ejectjust 7soluility/P0solutiondepends on a alance etween

lattice and hydration energies

so ]0solnless exothermic/more endothermic/more

positi"e for #a$!'so less soluble

!B so ]0solnmore exothermic/more negati"e/less

endothermic for Gg$!'so Gg$!'more soluble (1) '

[6]

3. (a) TPC

eat/enthalpy/energy change per mole for formation of a compound/

substance (1)

I@!B any mention of standard conditions or temperature

!ccept 7normal &' 7stale instead of 7standard

'eject energy required

&'

(nergy given out

(in a stated physical state) from its elements in their standard states (1) 2

41


42/122

(b) (i) ]0 4 (+*0&2 6 ') + (7 2'2 6 :) 7 (7 ':& 6 ')

4 7 *09 (%; mol7

) (2) I@!B sf

Correct answer with no wor%ing scores (2)

!ne mar% for correct use of all three coefficients

!ne mar% for correct use of signs throughout 2

(ii) 7 2: (%; mol7

)

I@!B sf

(c) (i) #ecause it is the more exothermic

(ii) TPC

changes the acti"ation energy for a reaction by changing themechanism/route (1)

lowers it for Beaction I more than for Beaction II

!B catalyst specific for Beaction I (1)

XComparison is essentialY 2

(d) (i)


43/122

(iii)

! 2

+

! 2

+

! 2

+ ! 2

$ ! '

+ $ !2 '

7

allow equivalent using the circled symol for en=eneY

Curly arrow from double bond/ circle towards of electrophile (1)

Correct intermediate& (if a bro%en ring is used for the delocalised

electrons it must extend o"er the other - carbons) (1)

Curly arrow from C7 >ondbac% into ring (1)

allow loss of 0>in the last step

(i") Any dinitrobenNene isomer !B any trinitrobenNene

(") TPC

delocalised (Z) electrons o"er the benNene ring (1)

!ccept delocalised pi system

'eject just )Delocalised ring*

'eject just )Delocalised onds*

substitution regains/retains the stabilisation energy (1)

!ccept staility for stailisation energy

which would be lost if addition occurred (1) [18]

3#. (a) (i) XCa(!)2Y 4 2-&0 6 '&2 6 :&- 4 90 (;)

XCa!Y 4 2-&0 6 '&2 6 2-&- 4 2:0 (;)

ot correct for mar%

Ignore negati"e signs in front of "alues / missing/wrong units

!ccept 1:A95 / 1:AA / 1:;; "

!ccept ::95 / :8 / :;; "

!nswers in k" acceptale

'eject 1:A "

'eject :: "

43


44/122

(ii) 0&9'

00&

4 0&0- mol

Answer must be decimalised

!ccept ;9;1C

'eject :C

1

/ ;9;1

(iii) ]4 0-&0

-&92

4 70 (%; mol7

) ( 2 s&f&)

]24 0-&0

-&2:99

4 7200 (%; mol7

) ( 2 s&f&)

stmar% for method (di"iding energy by number of moles)

2

nd

mar% for both answers gi"en to 2 sig fig and includingnegati"e signs&

2nd

mar% is dependant on st

2

!llow 2( from 3a63i6 and 3a63ii6

(b) (i) ]reaction4 ]7 ]2/rele"ant "alues being subtracted (1)

4 70 7 (7200) 4 + 90 %; mol7

(1)

Gar% independently

Jor 2nd

mar%H correct arithmetic sign and units needed 2

!llow 2( from 3a63iii6#gnore sig9 figs9

(ii) sing a lass >eaker / no lid is li%ely to lead to heat loss (1)

(glass) >eaker has significant heat capacity (1)

o apparent chec% made to ensure that Ca(!)2was heated

long enough/difficult to %now whether Ca(!)2was fully decomposed (1)


45/122

3+. (a) nthalpy/heat/energy change for one mole of a

compound/substance/ a product (1)

NO solid/molecule/species/element

'eject 7heat released or heat required unless oth mentioned

to be formed from its elements in their standard states (1)AMM!P normal physical state if lin%ed to standard conditions

'eject 7natural state / 7most stale state

standard conditions of atm pressure and a stated temperature (2* ,) (1)

'eject 7room temperature and pressure

'eject 7under standard conditions

(b) (i) #onds bro%en #onds made

` (+)*'- :7 (7)2': (1)

and

7 22-)(

0+)(

++

(1)

] 4 *'- +0 7 2':

4 7* sign and "alue (1)

]0[4 7* 4 7':&- (%; mol

7)

sign and "alue E on rd

mar% (1)

2 '

!ccept HC95 3k" molH1

6 with working (6)

!ccept > C95 with working 2a3 (7)!ccept >EA with working ma (/)

(ii)

( ) n t h a l p y

2 + ( ) 2

( 2 )

0

! B

7 *

!ccept HC95

Correct labelled le"els (1)

'eject 7'eactants and 7roducts as laels

] labelled (1)

direction of arrow must agree with thermicity

!ccept doule headed arrow

Diagram marks cq on sign and value of P0 in 363i6

#$%&'( activation energy humps 2

45


46/122

(iii) -07-00 .C (1)

!ccept any temperature or range within this range

higher temperature gi"es higher rate (1)

but a lower yield because reaction is exothermic (1)

!ccept favours endothermic reaction 2ore than eothermic solower yield

!B

Mower temperature gi"e higher yield because reaction is exothermic (1)

but rate is slower (1)

!ccept cq on sign of P0fin 363i6 or levels in 3ii6

'eject lower temp favours eothermic reaction

(i") Iron / Je (1) I@!B any promoters

no effect on yield (1) 2

(") temp would ha"e to be much higher for a reasonable rate then

yield would be too low

Klower acti"ation energyL implies reasonable rate

!B

Allows reaction at a lower temp at a reasonable/fast rate gi"ing

a reasonable yield&

!ccept rate too slow without catalyst at a temp giving a

reasonale yield

'eject to lower activation energy of reaction

(c) (i) ad"antage

higher (eEuilibrium) yield/more in eEuilibrium

mixture/eEuilibrium shifts to right (1)

because smaller number of (gaseous) moles/molecules on rhs (1)

#$%&'( any reference to change in rate 2

'eject just 7more ammonia

46


47/122

(ii) disad"antage

(plant more) expensi"e because thic%er pipes would be needed

&'

cost (of energy) for compressing the gases/cost of pump

!B

Cost of eEuipment/pressure not Uustified by higher yield

!ccept stronger or withstand high pressure for thicker

!ccept vessel/container/plant /equipment/reaction vessels for

pipes

'eject 7just more epensive

'eject 7just thicker pipes etc

'eject apparatus[18]

40. !"OR# si. i.s pro5ided / or -etter in (i) and (ii)

(i) ]< 4 2: .C (1) SAND A:ON/

eat change 4 0' 6 2:&0 6 '&0*40:0 ; (1) ignore sign at this point


48/122

41. (a) (i) E#r2O #r (1)

state symbols (1)

E #r2(g) O #r(g) scores only one

e&g&

E#r2(l)O #r(g) (2)#r2(l)O 2#r(g) (1) ie for state symbols

#r2O #r (0) 2

'eject wrong halogen or use of 7K (0)

(ii) nergy change when 1 mol (1)

!ccept heat or enthalpy for energyY

energy released instead of energy change

'eject 7energy required

of a solid/crystal/lattice (1)

is formed from its (isolated) gaseous ions (1)

I@!B standard states

"ust alanced equation

e9g9 %a>3g6 > l

H3g6 9%al3s6

can score only last two marks

(b) GgCl2has (a degree of ) co"alent character (1)

4ention of 7atoms or 7molecules scores (0)for all of 363ii6

due to polarisation of the anion (1)

(by4g2+

cation) 2

'eject just 74g>

3strongly6 polarising

48


49/122

(c) As group descended radius of42+

(ion) increases

!B cation increases (1)

!ccept reverse arguments

!ccept 7si=e instead of 7radius

'eject mention speciically of atoms 3e9g9 4g atoms6 or

molecules 34glmolecules6 scores (0)for all of part 3c6

Charge on ions remains the same/2+ (1)

!ccept correct formulae of cationsfor charge mark

!ccept 7charge density decreases scores one of the first two

marks

(down group) wea%er forces of attractionbetween ions (1)

'eject 7weaker onds

&' 7weaker onding

[10]

42. (a) (i) An ion which is unchanged during the reaction owtte

An ion which does not ta%e part in the reaction

'eject an ion which does not change its state

'eject use of word 7element instead of 7ion

(ii) $!'

27

(iii) \n + Cu2+

\n2+

+ Cu

#$%&'( state symols

!ccept Gn > u>>

Gn>>

> u

!ccept Gn > u>

@ Gn>

> u

49


50/122

(b) measuring cylinder

!ccept urette

!ccept pipette

!ccept volumetric pipette

!ccept graduated pipette

!ccept 5; cmApipette

!ccept pipette @ pipette filter

!ccept reasonale phonetic spelling e9g9 pipet, iurette

'eject eaker

'eject iuret

'eject graduated flask

'eject volumetric flask

'eject eaker or a pipette

'eject pepite

'eject conical flask

(c) Any two

polystyrene conducts heat less well than metals/less heat lost

to surroundings (1)

!ccept discussion of either polystyrene or metal

has a lower (specific) heat capacity/absorbs less heat energy (1)

1lastic inert whereas metal container might react (with Cu$!') (1) 2

(d) \inc -/:-&' 4 (0&09:-/0&0/0&09:/0&99) (1)

Copper sulphate -0/000 4 0&0- (1)

Copper sulphate / Cu2+

/ Cu$!' (1)

!ccept consequential on copper eing less than =inc

!ccept =inc is in ecess

I@!B sig figs

50


51/122

(e) (i)

9 0

: 0

- 0

' 0

0

2 0

0

0

< e m p e r a t u r e/ C

0 ' 0 0 2 0 : 0 2 0 0 2 ' 0

< i m e / s

a l l o w e i t h e r

correctly plotted points (1)7 All 9 (including 0 22)

must be correctly plotted

points Uoined by suitable lines (1)

!ccept curve/straight lines

XIf you cannot see a line chec% twice if still not "isible send to

re"iew as out of clipY 2

(ii) reaction not instant / so some time before all heat

energy released/measured (1)

!ccept energy lost

(temperature (slowly) declines) as heat energy gi"en out

(to the surroundings) (1) 2

'eject no temp change for first ; s ecause =inc has not een

added9 Slow to start

'eject temp slowly declines ecause reaction is complete

'eject no marks for descriing shape of graph without

eplanation

(iii) :: 7 :* .C

'eject 595 and less and E95 and more

51


52/122

(f) (i) -0 6 '&2 6 '- 4 *'-0 (;) for :9.C

Ignore units unless "alue and units are incompatible e&g&

*2'0 %; (0)

*&2' ; (0)

!ccept 2( from e3iii6e9g9

@ CC F rise @ EC;

8 @ C F rise @ E;

E @ C: F rise @ E8:;

5 @ CA F rise @ E;A;

3!llow minus sign6 ignore sign

:; @ C8 F rise @ 1;;8;

595 @ CA95 F rise @ E1A5

allow use of 5F even if different value in 3iii6

'eject 55 for mass of solution > =inc

(ii) Gax 1A8 3k" mol

H1

6for 1 mark

52


53/122

(iii) Incomplete combustion / combustion to C or C!& ot

complete combustion (1)

'eject not all of the propane urns9

'eject comments on accuracy of equipment9

(b) (i)C ( g ) + * ! 2 ( g ) C ! 2 ( g ) + ' 2 ! ( g )

+ : ' * 0 % ; m o l7

" F # 0 * ! # F 4 " 4

C ( g ) + ( g ) + 1 0 O ( )

+:'*0 4 ]0c+ (: 6 0- + 6 ':')

]0c

4+:'*0 7 '0 7 92

4 720-2 %; mol7

!ccept H;5; 3k" molH1

6

#alancing cycle with *!2 and 10 O() (1)

]4 (: 6 0- + 6 ':') 4 (+) -'2 (%; mol7

) (1)

Jinal "alue 720-2 (%; mol7

) (1)

#$%&'( SI

!llow 2( from an incorrectly calculated P01if method clear9

(ii) 2! is gas in eEuation/ not standard state!B mean bond energies differ from bond energies in these

compounds / n"ironment in these compounds changes bond

energies from the mean&

!ccept 0& is liquid in P0 comustion calculation ut ges in

ond energy calculation9

'eject 7mean ond energies are used without qualification

'eject all the sustances are in the gasous state

(c) (i) Jree radical (1)substitution (1) 2!ccept reverse order

53


54/122

(ii) 2C9W O C:'(1)


55/122

44. (a) (i) 22'5trimethylpentane

Ignore punctuation (Commas and hyphens may be interchanged)

!ccept ,C,C ] trimethylpentane

'eject pentan for pentane

]dimethyl]Cmethylpentane

,]dimethyl]C]methyl

pentane

]methyl]C,C]dimethyl

pentane

,C]trimethylpentane

(ii) C'*

!ccept 8018\ C0E

(iii) C2'

'eject 00

(i") 1ositi"e because energy is reEuired to brea% (C7C) bonds

(and not completely replaced (from new bonds made))

!B 1ositi"e because crac%ing reEuires (continuous) supply of

heat so must be endothermic

!ccept two H onds are roken and one @ made

'eject positive ecause it only occurs at high temperature

(") C+ 9/2 !2O C! + *2!

!B 2C+ 9 !2O :C! + 2!

!B C+ */2 !2O C + *2! (or doubled)

!xygen on left and correct formulae of products (1)

balancing (1)

$econd mar% depends on first and a sensible hydrocarbon

formula must be used& 2!ccept alanced equations including & and/or with &1:/ can e written 895 or 8^

!llow alanced equations ased on 8018with a smaller

alkane in the products for 1 mark eg

8018> &\ & > :01>0& (1)

55


56/122

(b) (i) Increase in pressureH o effect as number of

moles/molecules (of gas) doesn?t change during reaction (1)

Increase in temperatureH more NO as forward reaction

endothermic !P


57/122

(ii) EA or EA ut state that this is eothermic

If reaction mo"es to left hand side(1)

If reaction mo"es to right hand side (0) 2

(iii) add chlorine(1)

which dri"es eEuilibrium to the left(1)

&'

increase the (total) pressure(1)

because there are fewer (gas) molecules on left hand side(1)

&'

add 1Cl(1)

Phich dri"es eEuilibrium to the left(1) 2[8]

4". (a) (i) enthalpy/heat/energy change/produced X!< KreEuiredLYwhen one mole of gaseous ions(1)

are dissol"ed in eCcess ater6 to in$inite dil&tion (1) 2

(ii) #onds formed / attraction between(1)

cation and 7

!/lone pair (in water)

&'anion and + (in water)(1)

If bond between anion and cation (0) 2

(b) as magnesium has a much smaller ion (than barium ion)(1)

and has same charge &' charge shown(1)

so stronger attraction between ions(1)

!--&.stronger bonds between ions

Kcharge densityL scores 1 (o&t o$ $irst 2 marks)

#$%&'( references to polarisation and covalency of the ions

57


58/122

(c) (i) cycleH

for each labelled arrow Uoining correct species&

G g ( ! ) ( s )M a t t i c e n e r g y

G g ( a E ) ( + ) 2 ! ( a E )

0

h y d r a t i o n

s o l u t i o n

G g ( g ) ( + ) 2 ! ( g )

72 +

2

0

72 +

$pecies and stoichiometry(1)

$tate symbols(1)

Mabels appropriate to direction of arrows (1)!--&. numerical values

!--&.cycles using M

(ii) 0solution4 M + 0hydration &'numbers(1)

!* kJ mol1(1)onsequential on candidate*s cycle eg

calculation from cycle with one !gi"ing +--- %; mol

7(2) 2

B+2 correct answer with working (2) even if the 3c63i6 cycle is wrong

(d) Calculation of 0solutionof #a(!)2as 5-- %; mol7

&'

M down by :9- but 0hydrationdown by :-

!--&.M down but 0hydrationdown by less(1)

0solutionis more exothermic(1)

solubility is greater(1)

nd

mark dependent on 1st

Ard

mark dependent on nd

!--&.conseEuential mar%ing if solutionlessexothermic

[15]

4. (a) (i) Je2!+ C! 2Je + C!2(1)

04 ( 6 7*') 5 ( 6 70) 7 (722)

4 70 (%; mol7

) (2)

4ultiply y A twice(1)

orrect answer with sign(1)

!--&. consequential calculation if wrong stoichiometry

#f &given as product 1 maCon consequential calculation

58


59/122

(ii) (i) is more li%ely because the rate of a reaction between a solid

and a gas will be faster than that between two solids

!--&.

(i) is more li%ely because it is exothermic (and (ii) is endothermic)

&'

products in (i) are more thermodynamically stable relati"e to reactants than in (ii)

onsequential on 3a63i6

(b) (i) Mp4'

2

'

2

!p

p

(1)7p*s are essential%&X Y

4'

'

2&

:&

4 &: / &2 and no units(1) 2

onsequential on Mpepression provided no Ie or IeA&Cincluded

(ii) M1decreases(1)

TPC #ecause forward reaction release heat / exothermic

&'re"erse reaction absorbs heat / endothermic(1) 2

Dependent on Mpdecreases

Do notallow nd

mark if decrease is eplained in terms of position

moving to the left, +%-(SS moving is a consequence of Mpdecreasing9

(c) #$%&'( state symols

^H 22! + !2+ 'e()

'!(1) &' this &' multiples(1)

H Je Je2+

+ 2e()

/ Je 2e()

Je2+

(1)

#I ? and N not identified 1 (out o /)

iron() hydroxide (1)

!--&.Je(!)2/ XJe(!)2(2!)'Y

(d) co"alent bonds labelled(1)

dati"e bonds labelled &'shown as arrows(1)

!--&. dot and cross diagram(2)

Structure with Ie]Ie ond does not score first two marks


60/122

(e) (i) add (aEueous) sodium hydroxide / ammonia (1)!--&. !7

(aE)

red/brown/foxy red/red5brown/rust ppt/solid(1)

&'

add (aEueous) potassium hexacyanoferrate(II)/hexacyanoferrate(II)

ions(1)(1russian) blue==t6solid (1) 8!--&. result for near miss spelling

of reagent

&'

add (aEueous) potassium thiocyanate(1)

blood red (solution) (1)%&2ppt 2

(ii) Je+

polarises the (! bond in water) ligands(1)

XJe(2!):Y+

+ 2! XJe(!)(2!)-Y2+

+ !+

&' in words

eg deprotonation (of the ligand) >9the (sol"ent) water(1)

the !+/

+(aE) ions ma%e the solution acidic(1) 8stand alone

[19]

4#. (a) Difficult to decide when reaction complete/ reaction may be incomplete (1)

&' All CaC!may not decompose (1)

&' Difficult to measure temperature changes in solids (1)

&' ]2or ]0reactioncannot be determined because heat is supplied(1)

&'ecessary temperature cannot be reached (1)

&'o suitable thermometers (for measuring temperature change at high

temperatures) (1)

!--&. 7heat is required so temperature change will not e accurate

%&2 70eat is supplied so temperature cannot e

measured/ will not e accurate

(b) (i) Beaction occurs Euic%ly / incomplete reaction (in reasonable time)

with lumps(1)

eat losses occur if reaction isslo (1) 2

(ii) '&2 6 20 6 2&- 4 20 (;) &'0&20 %;

#$%&'( >/] signs

Incorrect units (0)

60


61/122

(iii) umber of moles of CaC!4 0&02 (1)

-00002&0

20=

(1)

]04 70-00 ; mol

7

&'70&- %; mol

7

(1)!--&. 2( from 3ii6

H1 for incorrect/missing sign/units

2hird mark depends on correct method for nd

mark

(i") ]0r4 ]07 ]02(1)4 70&- 7(7) ie use of 0ess

4 (+) 90&-/ (+) 9 ( %; mol7

) (1)

!--&. 29(9 from 3iii6

.atch for adding " to k" 2

(c) ($tandard) enthalpy (change) of formation (of calcium carbonate)

!(2 ]0formation/ ]0Fformation/formation

%&2 ]0f/ ]0.f

[10]

4+. (a) (i) (g) + !(g) + Cl(g) in top '0 o

2(g) + !2(g) + Cl2(g) in lower box

Brackets around the state symols are not required

(ii) -* 7 ::9 4 7 #(%; mol7

)

!--&. final answer on its own

(iii) ::9 7 ':' 4 (+)203(%;mol7

)

!--&. final answer on its own

(b) (i)

! C l! ! !!

! !

! !

! - - & . C l! !!

! !

! !

!

( 1 ) ( 1 ) ( 1 ) ( 1 )

!--&. all dots/crosses

!--&. 1 2a3if electrons are correct ut atoms are not identified

#f ionic dot and cross diagram (0) 2

61


62/122

(ii) 00 7 0:. (1)

as lone / non5bonding pairs ta%e up morespace/

repel more stronl9than bonded pairs (1)

%&2bonds being repelled/ and Cl being repelled 2

(c) o change (1)

as number of aseo&s reactant molecules 4 number of aseo&sproduct

molecules (1)

!--&. 1 2a3if candidates state or imply a very small change with correct

justification

eg Khardly changesL

Kdoesn?t change muchL

K"ery little effect/changeL 2[9]

*0. (a) Dynamic 7 reaction continuing (all the time) (1)

!--&.rate forward 4 rate bac%

Euilibrium 7 concentrations(of the substances) do not change /

remain the same (1)

%&2 >concentrations all eEual?

%&2 >amounts do not change? 2

(b) (i) -0 7 '-0 .C &' :205920 , (1)

_ - atm (1)

Lalues can e given in ka or k%m72

2

(ii) igh yield fa"oured by low temperature (1)

igh rate fa"oured by high temperature (1)

$o temperature used is a compromise (1)7 conditional on first two marks

!(2 correct inverse argument

(iii)


63/122

(c) (i) ]04 2]0f($!) 72 ]f($!2) 4 (7*- 6 2) 7 (7 2*9 6 2) (1)

4 7*: (%; mol7

) (1) #$%&'( units

7*: (%; mol7

) with some working (2)

%o consequential mark other than failing to multiply y two to get7* %; mol

7maC (1)

!ny positive answer (0) 2

TPC (ii) ]0fis de$inedas formation from elements

&']0fof an element is de$inedas 0 (in its standard state)

&'allelements are gi"en the "alue Nero

>It is an element? on its own (0)

(d) (i) 2!- &' 20-%&2name

%&22!

-&

#f name and formula given, ignore name9

63


64/122

(ii)

n c a t a l y s e d

C a t a l y s e d

u t h a l p y l e " e l s

n c a t a l y s e d

C a t a l y s e d

u t h a l p y l e " e l s

( )

( )

( )

( )

( )

( )

A M M ! P

( n t h a l p y /h e a t / e n e r g y )

( n t h a l p y /h e a t / e n e r g y )

1 r o d u c t s / 1 / $ !

B e a c t a n t s / B/ $ ! + !2 2

B e a c t a n t s / B/ $ ! + !2 2

1 r o d u c t s / 1 / $ !

!--&.endothermic intermediates

!--&.single hump for catalysed pathwayH (energy)

#f the diagram shows P0 endothermic, then can score the first two marks&

#f y]ais lael is wrong Ard

mark can not e awarded

atalysed and uncatalysed laels missing scores Ard

mark only

#f two diagrams drawn, full credit can e given if the catalysed

(ais clearly less than the uncatalysed9#f ]0 and (aconfused, thenmaC 2

TPC (iii) Changes mechanism to one of lower(a

&'to a different route with lower(a (1)

%&2KMowers(aL alone&

Beactants (chemically) adsorb on catalyst surface

&'(at gi"en


65/122

*1. (a) eat / enthalpy / energy change (for a reaction) / ]0(1)

is independent of the pathway / route (between reactants and products)

&' depends only on its initial and final state (1)

Both marks can score from a diagram and equation 2

(b) (i) ]04 ('x + '-) + (2x + '*)j (1)

+ (2x 7 0-) + ('x 7 ':')j (1)

#$%&'( signs for first two marks,ie mar%s for total

enthalpies of bonds bro%en and made&

4 7 90 (%;mol7

) (1)

Ard

mark is consequential on their values for first two marks

+ 90 (%;mol7

) (maC 2)

(ii) (nthalpy of) combustion

D& %&2 penalise 7standard

(iii) At atm pressure &' 0 / 00 %1a &' bar (1)

stated temperature (1)

!(22* , / 2- C 2

(i") Beaction has 2!(g) (rather than 2!(l)) (1)

$o not standard conditions (1)7 nd

mark is conditional on the 1st

A"erage bond enthalpies used (so not specific) (1 maC) 2

TPC (c) (xothermic so) products are at lower energy than reactants (1)

Reactantsare therefore thermodynamically unstable

(with respect to products) (1)Consequential on 1st

mark

%&2>reaction? or >system? is thermodynamically unstable

an argue from point of view of products9

(ais high (for noticeable reaction at room temperature) (1)

%&2>(ahigh? on its own

$o reactantsare %inetically stable(with respect to products) (1)

onsequential on Ard

mark

#f KreactionLinstead of reactants is used (3 maC) '[14]

*2. (a)


66/122

(b) (i) 29&0 cm!--&. &0 cm

(ii) *& 0&- .C

(c) (i) 0002(i)(b)

!--&. correct answer with no working

(ii) (c)(i)

(iii) (c)(ii) 6 -0

000

(1)

orrect answer H see tale elow(1) 2

(d) (i) -0 + (b)(i) (1)

6 '&2 6(000)

(b)(ii)

4 answer (1)

4ust use 363i6 in calculation to score nd

mark

#f the units are given, they must e correct 2

(ii)

=

=(iii)(c)0&0-

(i)(d)0

answer plus units

sign (1)

numerical answer using candidate?s figures to 2 or s&f& (1)%; mol

7(1) can e in " or M"

2ale of answers

(b)(i) (b)(ii) (c)(i) = (ii) (c)(iii) (d)(i)

/ %;

(d)(ii)

/ %; mol7

2:&0 *&'

*&:

0&0-2 &0' &00

&0:

7 -9&9

7 -&

2:&- *&'

*&:

0&0- &0: &02

&0

7 -9&0

7 -&

29&0 *&'

*&:

0&0-' &0 &0'

&0

7 -:&

7 -9&'

(e) Insulate calorimeter / (polystyrene) cup

!B put (calorimeter) in a (glass) bea%er

&'put a lid on [13]

66


67/122

*3. (a) umber of moles /2

/-0&09

-&=

(1)

#f candidate does first part only, working must e shown

umber of atoms 4 &0 6 02

(1)

!(2&0 &' &'&00(602)

%&2&02

#f all working shown, allow 2( for nd

mark #gnore units

orrect answer with no working(2) 2

(b) (i) 2Mi((s)) + 2+((aE)) O 2Mi

+((aE)) + 2((g))

!--&. multiples #gnore state symols

(ii)

+ +M i

+

C l+7

(1) (1)

!llow all dots or all crosses on lH

4a 1 if no/wrong charges

#f covalent 3;6

Do %&2 penalise if electrons not shown in pairs

4aimum 1 if -i and l not laelled

-i and l symols can go elow diagramSquare rackets not essential

!llow numer of protons/positive charges in nucleus as

alternative to symols for -i and l 2

(iii) Any two fromH


68/122

*4. (a) C0

!--&.(C-')2%&2(C:')2

(b) (i) 7:00

%&2+ :00

%&2:00

(ii) aphthalene is more/"ery stable than double bonds suggest (1)

4ust e a comparison for the 1st

mark


69/122

**. (a) (i) '

::'

4 ': (%; mol7

) #$%&'( 7> signs

(ii) energy needed to brea% bondsH

2 6 ': + * 4 (+)0:- (1)

energy change in ma%ing bondsH7' + 'x 7': + 2x 729: 4 (7) 2-:' (1)

enthalpy change 4 0:- 7 2-:' 4 7 '** (%; mol7

) (1)

X"alue and 7"e sign needed for rd

mar%Y

!--&. 29(9

>'** with wor%ing scores (2)

(b) C not in standard state / C not solid [5]

*". (a) (i)

!--&. H C

!--&. any correct representation that shows the structure

(ii) al%anes

(b) (i) enthalpy / heat / energy change when mole of substance / element orcompound (both) (1)

is burnt in excess oxygen (!< air) / completely / reacts completely (1)

with oxygen (1)

at atm pressure and specified or stated temperature

(ii) 2C'0+ !2 C!2+ 02!

correct formulae (1)

balancing (allow multiples of half "alues) (1) 2

69


70/122

(c) (i) Grof butane is -(g mol7

) (1)

-+

2+997

4 7'*&: / 7-0 (%; g7

) 7 conseEuential on Gr(1) 2

(ii) A comparison of any two or three fuels by mass (1)

&g& C'0gi"es out most energy per gram

A comparison of any two or three fuels by "olume (1)

&g& Cgi"es out more heat than ethanol per cm

A comparison of states e&g& C'0gas C2-! and CliEuids (1)

and conseEuence of state on use as fuel in motor "ehicle (1) '

&g& gases need big fuel tan% to be stored at high pressure

&' liEuids need smaller tan%

[13]

*. (a) (i) 1oints accurately plotted (1)

o straight lines of best fit& (1)

%&2 dot]to]dot, #$%&'( any other joining H up9 2

(ii) $uitable extrapolation to find maximum temperature rise at min (1)

alue from candidate?s graph 0&- .C (1)

('&-5''&-.C for accurate plot) 2

(iii) (


71/122

(ii) Density 4 g cm7

/ total "olume after reaction -0 cm/ total mass is -0 g&

!(2 g 4 cm

!(2 Density is same as that for water

!(2 eat capacity of metal is irrele"ant

%&2density 4

(iii) (&0 6 -0 / 000) 4 0&0-(0) (mol)

(i") (ii)(b)answer to

(i)(b)answer to

(1)

di"ide by 000 "alue negati"e sign (for units of %; mol7

)& (1)

!--&. answer in " molH1

if unit given9 2

#$%&'( SI9

(c) #mprovement is a stand alone mark, reason is not

!ny two fromUTPC Impro"ementH 1lace a lid on the polystyrene cup (1)

BeasonH Beduces heat loss (1)

Impro"ementH se a pipette or burette (to measure the "olume of solution) (1)

BeasonH Gore accurate (way of measuring "olume) (1)

Impro"ementH se more precise thermometer / digital thermometer (1)

BeasonH @i"es more accurate temperature cane(1)

Impro"ementH Gechanical stirrer / magnetic stirrer (1)

BeasonH to ensure complete / or faster reaction (1)

%&2 >spread heatS?

Impro"ementH Geasure temperature more oftenBeasonH Allows for better extrapolation (1)

!B can obtain a more accurate "alue of maximum temperature /

temperature change from graph '

%&2 repeating few times

%&2 Kcotton wool insulationL alone

%&2 more accurate weighing&[14]

71


72/122

*#. (i) 1otassium ion/ ,+larger than Ca

2+(1)

4ust notrefer to atoms

TPC , +smaller charge than Ca

2+(1)

Gust notrefer to atoms but CA say KpotassiumL has a smaller charge

3 than 7calcium6

harge density of M>is less than charge density for a

>without

eplanation is worth (1)out of these 1st

two marks

Mess attractionbetween (,+and I

7) ions(1)

%&2 just Kwea%er bondsL

!(2 reverse argument

#$%&'( references to etent of covalency

(ii) 1otassium ion / ,+lesspolarising (than Ca

2+) (1)

,I (close to) 00 F ionic / no co"alent character (1)

CaI2partially/ significantly co"alent

&'

Correct description of anion polarisation in CaI2%&2 just )distortion* of anion(1)

[6]

*+. (a) (i)

(1)

cycle with state symbols or as energy le"el diagram& (1)

labels (in symols, words or numers6(1)0soln4 70lat+ 0hydCa

2++ 2 6 0hyd!

7!B "alues

0lat4 7:-0 + 2 6 (7':0) 7 (7:&2) (1) '

4 7 2--&

72


73/122

(ii) $olubility increases down the group (1)

(if this is wrong, no marks availale in this part)

TPC

0hydof cation decreases / less exothermic (1)

but 0lattdecreases more(1)therefore 0solgets more exothermic / increases (1) '

(b) (i) Calcium hydroxide will be less soluble at the higher temperature (1)

(if this is wrong, no marks availale in this part)

because the reaction is exothermic (left to right) (1)

(an increase in temperature will cause a) decrease in te %al&e o$

(and (1) hence dri"e the eEuilibrium to the left)&

(ii)


74/122

(iii) ]04 000

(:0/0&0-)

4 + %; mol7

X2 $JY

answer (i) R (ii) (1)

sign units and 2 $J (1)

ndmark dependent on 1stunless clear method given!nswer can e calculated in " mol

H1

+ %; mol7

with no working(2)

+ 000 ; mol7

with no working(2) 2

(i")


75/122

(ii) lectron pairs/electron clouds repel allowing bigger angles

in three dimensions

&'

It is a three5dimensional shape being represented in two

dimensions

&'xplanation of why angles are not *0. in C/ are not 0.

in C! (1)

C! or C 4 0*. / 0*&-.

!B

C! 4 050-. (1)

!ngle can e stated rather than marked on the diagram ut

must e etween two onds, not etween two atoms

!--&.Kit is tetrahedral not flat/two dimensionalL

%&2K


76/122

(ii) 20* 4 ((C5) +((C5!) + (!5) (1)

4 (') +((C5!) + ':'

((C5!) 4 20* 7 2* 7 ':'

4 (+) : (%; mol7

) (1)

orrect answer with no working(2)

If C7 not multiplied by gi"ing (+):2 (%; mol7

) 1 maC 2

(iii)

Balanced cycle with state symols and data(1)

Calculation

]0f[+ 20* 4 9&* %; mol

7

IH$7 1#3.+ 203+ 7 201(.1) kJ mol

1

0essappliedcorrectlywithallowanceforC0(1)

7 whichwillgivecorrectsign

Answer with units (1)

!--&. 2( from use of 10 or wrong P0at

#f C0 not used allow 2( from cycle answer @ H 8553916 k" molH1

maC 2 (o&t o$ 3)

#f>AAk"molH1

usedinsteadofcorrect]0atanswer@3>615;19E/

3>615;k"molH1

maC 2 (o&t o$ 3)

*enalisesa2eerroronceO"+%

(i") Gore negati"e as energy is gi"en out when the liEuid forms (from

the gas)

&'Gore negati"e as more/stronger intermolec&larbonds/forces are made

#$%&'( type of intermolecular ond

76


77/122

(")

ydrogen bond/ dotted line between ! in one molecule and

hydroxyl hydrogen in another (1)

#ond angle 0. (1)7 must go across 0

nd

mark depends on correct atoms in ond

!--&. diagram showing methanol/ethanol

%&2 diagram showing methanol/ethanol and water

!--&. minor slip eg one missing 0 on a 0A 2

(d)


78/122

"2. (a) (i)

$tarts at Nero and approaching5axis (1)

Gaximum greater and at lower energy(1)7 2needsonlytoejust

higherthan212curvemustgoelow21curveapproachingthe]ais 2

(ii) As the temperature increases the energy of the particles increases (1)

se the diagram shading areas

&'more particles to the right hand side of Aline (1)

and so more (successful) collisions/particles ha"e energy greater /

eEual or greater than the acti"ation energy (1)

%&2KeEualL onitsown

%&2mentionof7frequencyofcollisionsonitsown

(iii) A catalyst pro"ides an alternati"e route with a lower acti"ation energy/

which reEuires less energy (1)

so more collisions / particles ha"e energy greater than the acti"ation

energy (1) 2

78


79/122

(b) (i) e&g&

Geasure the "olume of gas gi"en off in a gi"en time / count bubbles /

obscuring cross using limewater (1)

and then repeat o"er a range of temperatures (1)

No diarammaC 3

#f method shown cannot possily work maC 1ie waterath or

sensile range of temperatures B+2 %&2 different temperatures

1enalty

7 for poor diagram

'

(ii) 1ositi"e

mol goes to ' moles/particles (so more disorder) /increase in numberof moles/particles (1)

products include a gas (and so more disorder) (1)

%&2 mole of compound/element goes to ' moles of

compound/element

If Knegati"eL 0 (o&t o$ 2) 2

(iii) 1ositi"e withsomeeplanatione&g& ]$surroundings4 7 ]/< &'

because reaction is exothermic (1)

] is therefore negati"e and so ]$surroundingsmust be positi"e (1)#fnegativegivenin3ii6allow2(here 2

[15]

"3. (a) nthalpy / heat/energy change when mol of a substance(1)

%&2 7heat needed

is burnt in excess / burnt completely in air6oC9en (1)

under standard conditions of atm pressure = stated temperature / at 2* ,(1)

79


80/122

(b) #onds bro%en ' 6 C5 4 + 9'0

2 6 !4! 29:

**:

+=+=

(1)

#onds made 2 6 C4! 4 7 :0

' 6 7! '::7+-:7

==

(1)

] 4 + 29: + (7'::) 4 7 90(1)(%; mol7

)

(c)

C ( g ) + 2 ! ( g ) C ! ( g ) + ' ( g )

' ( g ) + C ( s ) + ! ( g )

2 2 2

2 2

'

Cycle(1)do not allow the word 7elements

!rrows laelled0fetc or numers (1)

]0r4 7 *' 7 (7 9-) 7 2 6 (72'2)(1)

4 + :-(1)(%; mol7

) '[10]

"4. (a) $tep II Pait before reading temperature/ ta%e a series of

(temperature) readings(1)!


81/122

(d) (i) eat calculated using candidate?s "alues in (c)

ignore or more $J at this stage

(ii) (7) 02-&0

))(( idto!nswer

Gethod conseEuentially(1)Answer sign and 27' $J(1) 2

T Vol Heat/kJ H/kJ mol1

7.0 22.5 1.39 55.6

7.0 23.0 1.40 56.0 / 56.2

6.9 25.0 1.44 57.7 / 57.6

[9]

"*. (a) nergy/heat change(1)!--&.nthalpy change

when gaseous ions(1)%&2Kone mole of gaseous ionsL

form mole of solid/crystal/lattice(1)%&2Kform one mole of an ionic

compoundL without physical state

&'

nergy change etc per mole(1)

$uitable eEuation(1)

$tate symbols(1)

If from its elements 0 (out of )

(b) (i) 8: 8 22 8 -* + '* 8 '0* 4 8 :2 (%; mol7

)

wor%ing(1)

answer(1)

orrect answer with no working(2)

> 8 with working(1)

.rong answer with only one error(1) 2

(ii) Mess endothermic due to wea%er (metallic) bonding(1)

Mi/Mi+is smaller &'vice versa in terms of potassium (1) 2

(c) (i) (Ionic) charge(1)$iNe/radius(1)

Charge density unexplained (maC 1) 2

(ii) co"alent character /Lnot 00 F ionicL/ Knot purely ionicL(1)

due to polarisation/distortion of anion/ Ag+is il9polarising(1) 2

81


82/122

(d) (i)

G ^ G ( a E ) + ^ ( a E )

7 0

0

l a t t

G ( g ) + ^ ( g )

S o m e i n d i c a t i o n i t i s 5 v a l u e s

s o l n

( s )

7+

+7

&'

energy le"el diagram

$pecies including state symbols(1)!--&. >/Hions

Arrows correctly labelled(1)

If M&& arrow k must be shown as 7M

!--&. a specific eampleeg aCl 2

(ii) ]solution4 7 Mattice energy + () hydration enthalpies

!--&.alance etween lattice energy and hydration enthalpies(1)the more exothermic ]solutionthe more li%ely the compound is to dissol"e

(1)7stand alone

&'

If () hydration enthalpies are greater than lattice energy(1)


83/122

"". (a) thermal decomposition / redox

%&2reduction or oxidation on their own

(b) (i) Jormation of mole of the compound/substance (1)

from its elements (1)

in their standard states/ under standard conditions/ (temperature

and pressure) at 2*, and atmosphere pressure (1)

(ii)

rloses formula mark 2 max

4ark independently formulae (1)

number of moles (1)arrows and state symbols (1)7 depend on one mark eing given for

the aove9

(iii) 0 / Nero (%; mol5

)

(i") ' 6 72'2 + 7'0 (&'7 20) 7 70 (1)

72* %; mol5

"alue (1)

signs and units (1)dependent on value eing one of these given

(c) xothermic + attempt at explanation (1)

#onds are formed when a gas turns to a liEuid (1)

!(2 answers ased on kinetic theory

"aporation is endothermic (therefore by ess?s Maw) the re"erse

must be exothermic 2[13]

83


84/122

". (i) Cl in ClH 7 / 7 Cl in Cl2H 0 (1)

! in 2!2H 7 / 7 ! in 2!H 72 / 27 (1) 2

(ii) hydrochloric acid/hydrogen chloride/chloride ion/ Cl/Cl7

%&2KchlorineL +%-(SS Kthe chlorine in ClL

(iii) %9B9 'ead whole thing through9-ook for good use of chemical language eg use of molecule / atom

!&& of 2 Cls has increased by ( 6 24)


85/122

(b) (i) 0c 4 X(7*') + (2 6 72:)Y 7 (79-)Y

4 7* %; mol7

7* %; mol7

with wor%ing (3)

7:0- %; mol7

with wor%ing (2)

all other >non5typo? "alues (max ) for 2 6 2:7* %; mol

7with no wor%ing (1)

(ii) (negati"e so) exothermic

(conseEuential on (i))

(c) C2-! + !22C!2+ 2!

species (1)

balancing (1) 2

(d) ,-4ust compare the two fuels for full marks

&nly dataHgenerated advantages and disadvantages to score9

Gethane is a gas and ethanol is a liEuid plus a "alid comment about

storage in %eicle e&g& methane reEuires ea%9container to store gas

under pressure / larecontainer reEuired to store gas whereas easy to

store liEuid in fuel tan% (1)

An9 2 o$

Gethane cheaper per %; of heat released (than ethanol)

Gethane cheaper (per tonne than ethanol)

Gethane produces more heat per gram (than ethanol)

heaper / more heat implies a comparison

(e) C2-! + X!Y CC! + 2! (1)not CC!

C2-! + 2X!Y CC!! + 2! (1) (allow CC!2)

Allow CC! + X!Y CC!! if CC! is a product in steEuation 2

(f) conc& 2$!'/Al2!/ conc or syrupy 1!'or names (1)

Jor acids conditionsH heat (if temp stated conc sulphuric -0 .C7200 .C

phosphoric -0 to 00.C)

Jor aluminium oxide conditionsH pass "apour o"er hot Al2!(1) 2

[16]

0. (a) (i) -&00 + '&0 4 0&0-*- mol

(ii) -0&0 6 '& 6 :&- (1)ignore sign

R 000 (1) 4 &:%; mar% conseEuentially

(&'*&%; if use --&0 g (1)) 2

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(iii) Answer to (ii) R answer to (i) (1)/correct method&

(expected answer +22&: to + 22&* for -0&0 g or +2'& to +2-& for

--&0g)

Answer with positi"e sign to sfs (1) 2

(b) (i) Increase temperature for a2C!and decrease for aC!(1)

Marger < with a2C!(or conseEuential on (a)(iii) (1) 2

(ii) o heat lost/gained to/from surroundings/reaction is complete

shc of the solution is the same as water

Allow cmof solution has a mass of g

Do not allow shc is '& ; g70

C7

[8]

1. (a) (i) 72'0 (%; mol7

)

(ii) 7:0 (%; mol7

)

1enalise incorrect units once only

(iii) !"erlap of p5orbitals / (system) (1)

(results in) delocalisation (1)

ma%es benNene (more) stable (by -2 %; mol7

)(1)

TPC

86


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(b) (i) Al#r / AIC/ Je#r/ Je

Jormula must be correctQ no names

(ii) Ignore curly arrows in this first stepQ mar% species only

(consistent with catalyst)

# r

# r# r

+

+

+ 7

++

# r + A l # r # r + A l # r2 ' ( 1 )

(1) (1) structure

(1) arrow

Alternati"e way of showing part played by catalyst

# r # r A l # r

Allow ,e%ul intermediate '

# r

+

(iii) lectrophilic substitution [11]

2. (a) (i) ichrome/platinum wire/ceramic rod (1)

cleaned in concentratedhydrochloric acid (1)

dipped in powdered sample and heated in flame (1)

both ideas needed for rd

point&

(ii) lectrons promoted/excited to higher energy le"els (1)

Jall bac% releasing energy as light of a particular freEuency

/wa"elength/emr (1) 2

(iii) $odium/a+

87


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(b) (i) '& 6 00 6 & (1)

4 ':0; / 0&':0 %;/'-*&; (1) 2

(ii) GrGg$!'&92! 4 2': (1)

2&/2': 4 0&0- (1)Allow


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(b) (i) 1(g) 1(g) + (g)

(ii) ess applied (1)

Gultiples (1)

Correct answer + *:(&2)/*:0 kJ mol1

(1)

(iii) Answer to (ii) di"ided by

+ 2(&)/20 kJ mol1

[10]

4. (a) (i) Gethanol is the biggest/ most complex molecule / greatest GB/most

atoms/most electrons

(ii) $system4 2*&9 7 *9&: 7 2(0&:)

4 72*&/ 72* ; mol7l

,7

Gethod (1)answer + units (1) 2

(iii) yes as molecules &'yes as (2) gases a liEuid

(i") $surr4 7/< (stated or used) (1)

4 7(72*/ 2*) 4 +0&' %; mol7

,7

/ +' ; mol7

,7

/+ '2&* (1)

7 for wrong units/ no units / more than ' $J

7 for wrong sign/ no sign 2

(") $total4 72*& + ' 4 +2&* / +2& ; mol7

,7

/ +2' ; mol7

,7

/

+0&2' %; mol7

,7

(1)

Kositi%eso =ossi>le(1) 2

(b) (i)


90/122

(c) (i) umber of molecules / fraction of molecules with energy (A/number

of molecules which ha"e enough energy to react&

(ii) ertical line / mar% on axis to show "alue to the left of line(A

[17]

*. (a) (i) nthalpy / heat (energy) caneon formation of mole of a compound (1)

from its elements (1)

in their standard states/ at atm pressure and stated

temperature (2* ,) (1)

(ii) (2 6 ') 7 (2 6 *0) (1)

04 7 2 %; mol7

(1)

+ 2 %; mol

7

or 7-: %; mol

7

(1) 2

(iii) enthalpy change conseEuential on (ii) (1)

acti"ation hump shown (1)

diagram properly labelled 7 with arrows named reactants and

products (1)

(i") 1roducts thermodynamically more stable than reactants exothermic

(") Beaction has a high acti"ation energy /reactants are %inetically stable

(b) (i) Dynamic 7 constantly mo"ing / still reacting/

Bate of forward reaction eEuals rate of re"erse reaction (1)

Euilibrium 7 concentrations/ amounts constant (1) 2

(ii) position of eEuilibrium mo"es right (1)

fewer moles/ molecules on B&&$& (1) 2

(iii) products remo"ed from reaction system/ not in the system for

long enough [16]

". (a) Density 4 &0 g cm7

&' cm(of water) weighs g

90


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(b) (< 4 & 7 *&- 4) &: (.C) calculated or correctly used (1)

000

:&++&'200

7 -&-/-&-- (%;) (1)

orrect answer with some working (2) 2

(c) (Gass used 4 *&9: 7 *9&: 4 ) &0 calculated or correctly used

(1)

Goles 4 0&':

0+&

4 0&02- / 0&02' (1) 2

(d) (c)Answer to

(b)Answer to

(1)

e&g& 02-&0

-&-

negati"e sign and %; mol7

(1)

answer correct to sf (1)

(e) (i) thanol "aporises/e"aporates (1)

(ii) Carbon/soot (1)

Incomplete com>&stion/insufficient oxygen so reaction does

not go to completion (1) 2[11]

. (a) (i) Gg(s) + Cu2+

(aE) Gg2+

(aE) + Cu(s)

entities (1)

state symbols (1) 2

(ii)

0_3r64 0_fXGg 2+(aE)Y 7 0_fXCu2+(aE)Y

entities including state symbols (1)

arrows (1)

ess applied (1)

91


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(b) (i) '&26-06:0 (1)

4 900 / 000 ; (1)

&'9& / kJ 2

(ii) 900 / -0000

4 0&09() (mol)

(iii) 000 6 0&09 /

4 &*(2) cm

!--&.


93/122

(b) A/ND/D (ignore units)

(5&0) + (7 2-5)j 7 (2 ':&2) + (7*&-)j

4 5 :& + '-&*

4 5 2&* %; (3)

Correct answer with some correct wor%ing (3)

Correct answer alone (1)

+ 2&* %; (2)

!mitting the 62 gi"es 79*& %; (2)

+ 9*& %; (1)

Incorrect application of ess?s Maw gi"es 70'&9 %; (2)

+ 0'&9 %; (1)

Incorrect ess?s Maw and omit 62 gi"es 70-&- %; (1)

+ 0-&- %; (0)

NO A/ND/D (ignore units)

(:2&2) + (72-&)) 7 ((2 ':&2) + (7*&-)j (1)

4 5 *&0 + '-&*

4 5 '2& %; (3)


Correct answer alone (1)

+ '2& %; (2)

!mitting the 62 gi"es 7 '9& %; (2)

! '9& %; (1)

Incorrect application of ess?s Maw gi"es 7 '0&* %; (2)

! '0&* %; (1)

Incorrect ess?s Maw and omit x2 gi"es -9& %; (1)

+ -9& %; (0)[6]

#0. (a) A species with a lone pair / pair of electrons (1)

NO Knegati"e ionL alone or as an alternati"e

which it uses / donates to form a (dati"e) co"alent bond (1) 2

93


94/122

(b) (i) Ammonia / (in ethanol) (1)

heat (1)NO heat under reflux +%-(SS in a sealed tube

#f a temperature is quoted it must e greater than 1;;

in sealed tube / under pressure / concentrated (1)#f a pressure is quoted it must e greater than 1 atm

Conditions are dependent on correct reagent&

If ammonia and an additional reagent maC (1) for two correct conditions&

(ii) Carbon5bromine bond stronger / higher bond enthalpy than

carbon 7 iodine / a for C5#r is higher than C5I

LNOR/any extra explanations in"ol"ing the al%yl groups

(c) Identify bonds bro%en and made (1)

e&g& nergy in + ':' or + '0

AND nergy out (5) :-: or (5) -2 (1)

nergy needed to brea% bonds 7 energy released to ma%e bonds 4 : (1)

e&g& C5I + ':' 7 :-: 4 + :

or C5I + '0 7 -2 4 + : (1)

Correct e"aluation dependent on use of : (1)

i&e& C5I 4 22 %; mol7

(1)


If final answer is negati"e max (2)

If : is on the wrong side then -: max 2 (5-: (1))

If miss out : then *2 maC 1

(d)

C C !! A : : O - !

[10]

94


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#1. (a) for energy le"el of product lower than reactant both labelled with species (1)

for acti"ation hump (1)

for abeing correctly mar%ed (1)

!rrow must not point downwards for 0being correctly mar%ed (1)

e&g&

n t h a l p y

x t e n t o f r e a c t i o n

A + ( )

( 2 ) A

2 2

a

'

(b) (i) starts at or near origin (not on x or y axis) s%ewed distribution that is

reasonably asymptotic to the x5axis (1)

for uncat(must not be to the left of the pea%) (1)

for catto the left of uncat(1)and still not to the /eft of the peak

A o o fG o l e c u l e s

e & g &

c a t

u n c a t

a

a

n e r g y

(ii) Pith the catalyst a greater number/proportion of the molecules (1)

2his point must e linked to the diagram in some way, e9g9

laelled shading

ha"e cat/ sufficient energy to react (1)

and so more collisions result in reaction / more successful

collisions (1)

95


96/122

(c) At 2-C no / few molecules / collisions ha"e a&/

sufficient energy to react (1)

At higher temperature the (a"erage) energy of the molecules

increases (1)

At '00C a greater proportion of the molecules/collisionsha"e energy greater than/eEual to the acti"ation energy (1)

[13]

#2. (a) Mc4[ ][ ]

(1)2

2'

'22

!C

YXYC!X

Starting amounts:

(1)

==

==

mol0&molg+/g-'!

mol:2-&0molg:/g0C

2

'

Equilibrium amounts:CH4= 0.625 2.0 = 0. 1 25 mol (1)

H2O = 3.0 2.0 = 2.0 mol (1)

CO2= 0.0+ 2.0 = 0.500mol (1)

H2= 2.0 mol (given

Equilibrium concentrations:

!"ove v!l#e$ % 4 &m3

(1) (m!' )on$e*#en+l,

[CH4]= 0.03125 mol &m-3

[H2O] = 0.500 mol &m-3

[CO2] = 0.125 mol &m-3

[H2] = 0.50 mol &m-3

2

'

2

eE2eE'

'

eE2eE2

c-00&00/2-&0

-0&0/2-&0

Y!XYCX

YXYC!X,

==

4 &0 (or or &00) (1)mol2dm

5:(1)

(b) 04 (5*') 7 X(59:) + (2 6 7 2'2)Y (2) 1 mark for ? , 1 mark for signs and values

4 + :: (1)%; mol7

1 scores =ero

96


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(c) A catal9st (of nic%el) is used because the reaction e"en at 9-0.C is too slow /

to speed up the reaction (1)

en any siC of the following eight pointsH

a tem=erat&re of 9-0.C is usedH

as the reaction is endothermic (1)

a high temperature increases the "alue of the eEuilibrium constant (1)

and so increases the eEuilibrium yield (1)

a high temperature also fa"ours a fast rate (1)

but a temperature _ 9-0 would be too expensi"e / cause engineering

problems (1)

em=erat&re co&ld score &= to * >&t maC " $or and K com>ined.

#f their calculation in 36 gives an eothermic answer, mark consequentially

eothermic 316, decreases Mp 316, decreases yield 316 ut faster rate316, so :5; is

compromise of fast rate and lower yield 316T

A =ress&re of 0 atm is used

e"en though the reaction goes from to - gas moles

Enne Retics Ans

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