Ans Chem 2011 the Times

7/28/2019 Ans Chem 2011 the Times

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SOALAN ULANGKJI SPM 2011

W

Chemistry Jawapan

Chemistry Paper 1

No Ans No Ans No Ans No Ans No Ans1 D 11 A 21 C 31 A 41 D2 C 12 B 22 A 32 D 42 D3 C 13 B 23 C 33 C 43 D

4 A 14 C 24 A 34 D 44 D5 C 15 B 25 B 35 A 45 C6 D 16 B 26 D 36 C 46 B7 D 17 C 27 C 37 D 47 B8 D 18 D 28 C 38 C 48 D9 A 19 A 29 A 39 C 49 B10 B 20 C 30 C 40 B 50 B


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l e h d i d a p a t i

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Chemistry Paper 2

Ques ion Mark scheme (sample answer) Sub Mark o al ma1(a)

(b)(i)(ii)

(c)(i)

(ii)

(d)

(e)

Polimerisa ion

E hene As plas ic bag

Cl H| |

C C | |H H n

Cheaper // ligh er

- I non biodegradable // canno compose by bac eria- when i is burn , produce poisonous gases

Isoprene // 2-me hylbu -1,3-diene

1

11

1+1

1

11

1o al

2

9

2.(a)

(b)

(c)

(d)(i)

(ii)

(iii)

(e)(i)

(ii)

Number o pro on in nucleus o a om

- Size decrease // size become smaller- because when pro on increase, elec ron also increase- orce atrac ion be ween nucleus and valence elec ron increase

Pro on : 12Elec ron : 10

Covalen bond

SH2

34

Cl // chlorine

Hydrochloric acid

1

111

11

1

1

1

1

1o al

3

2

11


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3. (a)

(b)(i)

(ii)

(iii)

(c)(i)

(ii)

(iii)

- Te decomposi ion/break down o elec roly e in o heir cons i uen s- by using elec rici y

Chlorine gas

- Cl- ions are selec ive discharged- because Cl- ions are more concen ra e han OH- ions

2Cl- Cl2 + 2e- able wri e reac an s and produc correc ly - able o balance correc ly

Become hicker // grey shiny me al deposi ed // mass o silver increase

Silver me al

ype o elec rode used

11

1

11

11

1

1

1o al

2

2

2

104 .(a)

(b)

(c)(i)

(ii)

(d)(i)

(ii)

(e)

Green

Copper(II) sulpha e

Sodium carbona e // po assium carbona e

Double decomposi ion reac ion

H2SO4 + CuO CuSO4 + H2O- able o wri e reac an s correc ly - able o wri e produc s correc ly

- mol o CuSO4 = 0.2(30)1000

= 0.006

- 1 mol o CuSO4 produce 1 mol o X Mol o X = 0.006

- mass o X = 0.006 x 160= 0.96 g ....wi h correc uni

Hea ed s rongly

1

1

1

1

11

1

1

1

1o al

2

3

10


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5. (a)(i)

(ii)

(b)(i)

(ii)

(c)(i)

(ii)

Hydroxyl group

H H H H H H| | | | | |

H C C C OH H C C C H| | | | | |H H H H OH H

Es eri ca ion

Propyl e hanoa e

2C3H7OH + 9O2 6CO2 + 8H2O- able o wri e reac an s and produc s correc ly - able o balance correc ly

- mol o P = 3.060

= 0.05

- 1 mol o P need 4.5 mol o oxygen gasMol o oxygen = 0.05 x 4.5

= 0.225

- volume o oxygen gas = 0.225 x 24= 5.4 dm3 .....wi h correc uni

1

1+1

1

1

11

1

1

1

o al

2

2

3

106. (a)

(b)(i)

(ii)

(c)

(d)

(e)

Hea change/release when 1 mol o subs ance is burn comple ely in excess oxygen

- mol o bu anol = 0.37 = 0.00574- Q = 0.005 x 2679 kJ = 13395 Joule ........wi h correc uni

13395 = 500 x 4.2 x = 6.4OC ........... wi h correc uni

energy 2C3H7OH + 9O2

H = - 2679 kJmol-1

6CO2 + 8H2O

- Axis wi h energy level- Correc reac an s and produc s

- hea is absorbed by copper can- hea is released o he surrounding- incomple e combus ion occurred

- increase- because more hea is released when he more o carbon dioxide and wa er molecules are ormed.

1

1

1

1

11

111

11o al

2

2

Max.2

210


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7.(a)(i).

(ii)

(b)

(c)

- e.g : sulphuric acid- acid ha produce 2 mol o H+ ions rom 1 mol o acid

- e.g : hydrochloric acid // ni ric acid- acid ha produce 1 mol o H+ ions rom 1 mol o acid

- Reac wi h me al o produce hydrogen gas- e.g : 2HCl + Mg MgCl2 + H2

- able o wri e correc ormula or reac an s and produc s- able o balance correc ly

- Reac wi h me al carbona e o produce carbon dioxide gas- e.g : 2HCl CaCO3 CaCl2 + CO2 + H2O


- Reac wi h me al oxide o produce sal and wa er- e.g : 2HCl + CuO CuSO4 + H2O


- Ma erials & appara us : 250 cm3 volume ric ask, elec ronic balance, glass rod. 100 cm3 o beaker, po assium hydroxide pelle s and dis illed wa er.

- mol o KOH = 250(1.0)1000

= 0.25

- mass o KOH = 0.25 x 56= 14 gram

- weigh 14 g o po assium hydroxide pelle s.- pu he po assium hydroxide in o he beaker and add some dis illed wa er.- S ir he solu ion un il all po assium hydroxide dissolve comple ely - Pour he solu ion in o 250 cm3 volume ric ask.- Rinse he beaker using dis illed wa er and pour i in o volume ric ask - Add he dis illed wa er slowly in o volume ric ask un il he calibra ion mark.- shake he solu ion well

11

11

1

11

1

11

1

11

Max. 6

1

1

1

1111111o al

4

6

1020


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8.(a)(i)

(ii)

(iii)

(b)

- Pour 2 cm3 o e hane and e hene in o wo di eren es ubes.- Add bromine wa er // acidi ed po assium managana e(VII) in o he bo h es ubes- Shake he bo h es ube well- No change is observed or e hane- E hene will decolourised brown colour o bromine // purple colour o acidi ed po assiummangana e(VII) o colourless- because e hene has double bond be ween carbon a oms

- % carbon in e hane = 2(12) x 10030

= 80.0% - % carbon in e hene = 2(12) x 100

28= 85.7%

- E hene has higher percen age o carbon a om per molecule- E hene produce more soo iness

- hydrogena ion- C2H4 + H2 C2H6- Ca alys : Nickel // pla inum

Vulcanised rubber Unvulcanised rubberElas ici y - elas ic - More elas ic

- because i has sulphur cross link Resis an owardOxida ion

- easily o oxidise- because i has double bond

be ween carbon a oms

- more resis an o oxida ion

Resis an oward highempera ure

- easily become sof and s icky a high empera ure

- more resis an o highempera ure because i has higher

rela ive molecular mass.

11111

1

1

1

11

111

o al

6

4

3

720


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9.(a)(i)

(ii)

(iii)

(iv)

(b)(i)

(ii)

- N2 + 3H2 2NH3 - able o wri e reac an s and produc s correc ly - able o balance he chemical equa ion correc ly

- Ca alys : Iron powder- empera ure : 450OC 550OC- Pressure : 250 a mosphere

- mol o hydrogen gas = 7.224

= 0.3

- From equa ion, 3 mol o hydrogen gas produce 2 mol o ammonia,So, 0.3 mol hydrogen gas produce 0.2 mol o ammonia.

- Volume o ammonia produce = 0.2 x 24 dm3= 4.8 dm3

- % o N in NH4NO3 = 2(14) x 10080

= 35.0%

- % o N in (NH4)2SO4 = 2(14) x 100132

= 21.2%

- Ammonium ni ra e has higher percen age o ni rogen- Ammonium ni ra e beter or armer

- Use in manu ac ure o er ilisers- Use in manu ac ure o de ergen- use as elec roly e in car bateries- use in manu ac ure o pain pigmen

- Sulphur dioxide dissolve in rain wa er- produce acid rain- Acid rain corrode he building when i reac wi h me als and marmar.

11

111

1

1

1

1

1

1

1

11

1111

111

o al

2

3

3

6

Max. 3

3

20


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10.(a)

(b)(i)

(ii)

(iii)

(c)(i)

(ii)

- Reac ion I is non redox reac ion- because no change in oxida ion number or every elemen- Reac ion II is redox reac ion- because oxida ion number o chlorine change rom 0 o -1 // oxida ion number o brominechange rom -1 o 0

- in ensi y o blue colour decrease- magnesium s rip dissolve // mass o magnesium decrease- brown me al was deposi ed

- oxida ion : Mg Mg2+ + 2e- reduc ion : Cu2+ + 2e Cu

- Oxidising agen : copper(II) ion- Reducing agen : magnesium me al

- Process when he iron release i s elec ron- wi h he presen o oxygen and wa er

es ube A - Te in ensi y o blue colour is low - Iron nail rus bu litle only

es ube B- Te blue in ensi y is high- he iron nail rus heavily - because iron is more elec roposi ive hen copper in elec rochemical series.

es ube C- Te in ensi y o pink colour is high // he bubbles gas is released- iron nail is no rus- because iron is less elec roposi ive han magnesium in elec rochemical series

111

1

111

11

11

11

11

111

111o al

4

Max.2

2

2

2

2

3

Max. 320


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1.(a)

(b)

(c)

(d)

(e)(i)

(ii)

(iii)

( )

(g)

(h)

- 23.0- 18.0- 14.0- 10.0- 7.5- 3 marks : All correc reading wi h 1 decimal poin- 2 marks : All correc wi hou decimal poin or 4 correc o 1 decimal poin- 1 mark : any hree correc (wi h or wi hou 1 decimal poin )

Experimen Concen ra ion o HCl (moldm-3) ime aken 1/ (s-1)1 0.10 23.0 0.0432 0.20 18.0 0.0563 0.30 14.0 0.0714 0.40 10.0 0.1005 0.50 7.5 0.133

- 3 marks : all 4 column correc wi h hree decimal poin or 1/- 2 marks : all 4 column correc wi hou decimal poin or 1/- 1 marks : no uni or each column and wi hou decimal poin or 1/

Mg + 2HCl MgCl2 + H2 - 3 marks : all correc ormula or reac an s, produc s wi h balanced.- 2 marks : all correc ormula or reac an s, produc s wi hou balanced.- 1 mark : correc any reac an s or produc s

Te higher he concen ra ion o hydrochloric acid he shor es ime aken or magnesium ribbon

dissolves.Manipula ed : concen ra ion o HCl

Responding : ime aken or magnesium dissolves

Cons an : leng h / size o magnesium ribbon

- 3 marks : all axes are labelled wi h correc uni , all poin ploted correc ly and smoo h line- 2 marks : all above bu axes labelled wi hou uni or correc any wo- 1 mark : any sui able answer.

- 11.5 s // hal - sulphuric acid is dipro ic acid whereas hydrochloric acid is monopro ic acid.- sulphuric acid con ain wice o H+ ions compare o hydrochloric acid- 3 marks : all correc- 2 marks : any wo correc- 1 mark : any one correc

- higher concen ra ion o HCl con ain more number o H+ ions per uni volume- requency o collision be ween Mg and H+ ions increase- requency o e ec ive collision increase, ra e o reac ion increase- 3 marks : all correc- 2 marks : any wo correc- 1 mark : any one correc

3

3

3

31

1

1

3

111

111

3

3

3

Chemistry Paper 3


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(i)

(j)

- hydrochloric acid is s rong acid, e hanoic acid is weak acidhydrochloric acid ionise comple ely in wa er, e hanoic acid ionise par ially in wa er- hydrochloric acid produce higher concen ra ion o H+ ions han e hanoic acid- 3 marks : all correc- 2 marks : any wo correc- 1 mark : any one correc

S rong acid Weak acidHydrochloric acidSulphuric acidNi ric acid

E hanoic acidCi ric acid

- 3 marks : all correc- 2 marks : any wo correc- 1 mark : any one correc

111

3

o al

3

302.(i)

(ii)

(iii)

(vi)

(v)

(vi)

- Wha is he hardness o pure copper compare o ha o bronze?

- Te harder he subs ance, he smaller he diame er o den produced. - Manipula ed : Bronze and copper block - Responding : Diame er o den produced- Cons an : s eel ball, mass o weighed, dis ance o weighed rom he block .

- Brass block, copper block, me er ruler, 1 kg o weighed, re or s and, s eel ball, hread andcellophane ape.

1, A s eel ball is aped on he copper block using a cellophane ape.2. 1 kg o weighed is suspended abou 1 me er rom he copper block.3. Te weighed is released o he s eel ball on he copper block 4. Te den produced is measured using he ruler.

5. S ep 1 un il 4 are repea ed wice o ge he average o den produced.6. Experimen was repea ed by replace he copper block wi h brass block.

Diame er o den1 2 3 Average

Copper block Bronze block

3

3

3

3

3

3o al 18

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Ans Chem 2011 the Times