Spm Trial 2012 Chemistry a SBP

1

BAHAGIAN PENGURUSAN SEKOLAH BERASRAMA PENUH

DAN SEKOLAH KECEMERLANGAN

KEMENTERIAN PELAJARAN MALAYSIA

CHEMISTRY

TRIAL-EXAM

SPM 2012

MARKING SCHEME

PAPER 1

PAPER 2

PAPER 3

http://www.chngtuition.blogspot.com

2

SKEMA KERTAS 1

PENTAKSIRAN DIAGNOSTIK AKADEMIK

SBP 2012

CHEMISTRY 4541/1

1 A 26 C

2 A 27 D

3 C 28 C

4 A 29 D

5 A 30 B

6 D 31 B

7 B 32 C

8 A 33 A

9 B 34 C

10 A 35 C

11 B 36 D

12 A 37 A

13 D 38 B

14 C 39 B

15 D 40 D

16 A 41 D

17 B 42 D

18 D 43 A

19 C 44 B

20 B 45 C

21 C 46 B

22 D 47 C

23 D 48 B

24 B 49 D

25 A 50 C


3

MARKING SCHEME

CHEMISTRY PAPER 2 SECTION A (4541/2)

Question Mark scheme Sub

Mark

Total

Mark

1(a) A: Detergents

B: Soap

r : sodium salt

1

1

2

1(b)(i) magnesium ion // or calcium ion

r : Mg2+

, Ca2+

1

2 1(b)(ii) Soaps are biodegradable 1

1(c) Analgesics

Psychotherapeutic

r: wrong spelling

1

1

2

1(d)(i) Sugar

Aspartame

1

1

3

1(d)(ii) To add / restore the colour of food // To enhance its visual

appeal / appearance// more attractive

1

TOTAL 9


Mark

Total

Mark

2(a)(i) Magnesium

r:Mg 1

2

2(a)(ii) Has 3 shell occupied with electrons 1

2 (b)

1. Proton number of chlorine is higher than magnesium // the

number of proton of chlorine atom higher than magnesium atom

// total positive charged in nucleus higher than magnesium

2. The attractive force between the nucleus and the electrons in

chlorine atom stronger than magnesium atom // nuclei attraction

towards electrons stronger.

1

1

2

2(c) Light bulb // in welding process 1 1

2 (d) Argon 1 1

2(e)(i)

3 Cl2 (g) + 2 Fe (s) 2 FeCl3(s)

1

1

2(e)(ii) Mass iron (III) chloride = 0.05 x 161 // 8.05 g 1 1


4

2(e)(ii)

1

1

Total 9


Mark

Total

Mark

3(a)(i) 6 1

4

3(a)(ii) To estimate the age of fossils and artifacts 1

3(a)(iii) C-12 // C-13

1

3(a)(iv) 7 / 6 1

3(b)(i) A: covalent

r: covalent bond

B: ionic

r: ionic bond

1

1

6

3(b)(ii) 2.8.8.1 1

3(b)(iii) High melting point and boiling point // conduct electricity in

molten or aqueous solution // soluble in water // insoluble in

organic solvent.

[Any one]

1

3(c)(iv) 2K + Cl2 2KCl

1. Formula of reactants and products correct

2. Balance the chemical equation

1

1

TOTAL 10

13

C 6

12

C 6

Or

Hot iron wool

Wul besi panas

Heat

Panaskan

Chlorine gas

Gas klorin

√


5


Mark

Total

Mark

4(a)(i) Pipette

r: wrong spelling 1

3

4(a)(ii) Phenolphthalein // methyl orange

r: wrong spelling 1

4(a)(iii)

Phenolphthalein : pink to colourless //

methyl orange : yellow to orange

1

4(b)(i)

2KOH + H2 SO4 K2 SO4 + 2H2O

Formula of reactants and products correct

Balance the chemical equation

1

1

2

4(b)(ii)

1. Mol of KOH = (1.0)(25) / 1000

= 0.025 mol

2. Molarity of H2 SO4 = (0.0125)(1000) / 10

= 1.25 mol dm-3

//

Molarity of H2SO4 = 0.0125 /0.01 = 1.25 mol dm-3

Or

b

a

VM

VM

bb

aa ; Molarity of H2SO4 = 10

)25(1

2

1x

= 1.25 mol dm-3

r: wrong unit or without unit

1

1

2

4(c)(i) Hydrogen ion

r: H+ (symbol ion)

1

3 4(c)(ii)

1. no water

2. contain of molecule // no hydrogen ion, H+

1

1

TOTAL 10


6


Mark

Total

Mark

5(a) Chemical formula that shows the simplest whole number ratio of

atom of each element in the compound.

1 1

5(b)(i) Mass of Mg = 2.4 g

Mass of O = 1.6 g

1

6

5(b)(ii) Mole of Mg = 2.4 / 24 = 0.1

Mol of O = 1.6 / 16 = 0.1

Mg : O = 1 : 1

1

1

5(b)(iii) MgO 1

5(b)(iv) to allow oxygen enter the crucible 1

5(b)(v) Repeat the process heating, cooling and weighing until a

constant mass is obtained.

1

5(c)

Apparatus set-up correct and functional

Labeled : magnesium ribbon, heat

1

1

2

5(d)(i) Zinc oxide // aluminium oxide

r: formula

1

2

5(d)(ii) Silver is less reactive / not reactive metal 1

TOTAL 11

Magnesium

ribbon

Heat

crucible


7


Mark

Total

Mark

6(a) Hydrogenation 1

5

6(b) C4H8 + H2 C4H10 1

6(c)(i)

Mole of butene = 2.8 /56 = 0.05 mol

1

6(c)(ii) P1. 1 mol of butene burns in oxygen gas produce 4 mol of

carbon dioxide.

Therefore 0.05 mol of butene burns in oxygen gas produce 0.2

mol of carbon dioxide //

C4H8 : CO2

1 : 4

0.05 : 0.2

P2. volume of CO2 = 0.2 x 24 = 4.8 dm3

1

1

6(d) P1: 2 cm3 of but-2-ene and 2 cm

3 of butane gas are filled in two

different test tubes.

P2 : 2 -3 drops of acidified potassium manganate (VII) solution

is added to both test tubes.

P3: But-2-ene decolourises purple acidified KMnO4

Purple acidified KMnO4 in butane remains unchange.

Or

P1: 2 cm3 of but-2-ene and 2 cm

3 of butane gas are filled in two

different test tubes.

P2 : 2-3 drops of bromine water is added to both test tubes.

P3: But-2-ene decolourises brown bromine water.

Brown bromine water in butane remains unchange.

1

1

1

Or

1

1

1

3

6(e)(i) A: unvulcanised rubber

B: vulcanised rubber

1

1

3

6(e)(ii) Rubber type B/ vulcanised rubber is more elastic than rubber

type A/ unvulcanised rubber

1

TOTAL 11


8

SECTION B

Question Mark scheme Mark Σ

Mark

7 (a)

(i) Ascending order : Cu, Y,X, W

(ii)

P1 : Positive terminal : Cu

P2 : Potential difference : 1.3V

P3: Copper is less electropositive // X is more electropositive

correct value and unit

1

1

1

1

4

7 ( b) (i)

Experiment I : Pb 2+

, Cl-

Experiment II: H +

. OH- , Cl

–

r: lead(II) ion, chloride ion

Hydrogen ion, hydroxide ion, chloride ion

1

1

2

7(b)(ii)

Experiment 1 Experiment II

Product at anode:

Chlorine gas

Products at cathode:

Oxygen gas

Reason:

P1: Cl-

is discharged

P2: the only

anion presence

and discharged at anode

Reason:

P1:OH- is selected to be

discharged

P2:the position of OH- is lower

than Cl- in electrochemical series

.Half equation:

2Cl-

Cl 2 + 2e

P1:Correct formula of

reactant and product :

P2: Balance equation

. Half equation:

4OH- 2 H2O + O2 + 4e

P1: Correct formula of reactant

and product

P2: Balance equation

1 + 1

1 + 1

1 + 1

1 + 1

1 + 1

10


9

7(c)

P1: Positive terminal: R

P2: Negative terminal:Cu

P3: Suitable metal for R : Silver

P4: Suitable solution for R : Silver nitate solution

1

1

1

1

4

Total 20

Question Mark scheme Mark Σ Mark

8(a) P1. Smaller size has larger total surface area.

P2. Absorb heat faster.

P3. Bigger size has smaller total surface area.

P4. Absorb heat slower

1

1

1

1

4

(b)(i) Copper(II) sulphate 1 1

(b)(ii) 1. Experiment I

Rate of reaction = 40/2 = 20 cm3 min

-1

2. Experiment II

Rate of reaction = 60/2 = 30 cm3min

-1

1

1

2

(b)(iii) P1. Rate of reaction in Experiment II is higher than

Experiment I.

P2. Substance X used in Experiment II is a catalyst.

P3. Catalyst provided an alternative path with requires a

lower

activation energy.

P4. More particles are able to achieve lower activation

energy.

P5. Frequency of effective collisions between zinc atoms and

hydrogen ions are higher.

1

1

1

1

1

5


10

(b)(iv) 1. Label of axes and unit

2. Correct curve and label

1

1

2

(v) 1. Correct formula of reactants and product

2. Balanced equation

Zn + 2H+ Zn

2+ + H2

1

1

2

(vi) 1. Rate of reaction using sulphuric acid is higher.

2. Volume of hydrogen gas released is doubled.

3. Sulphuric acid is a diprotic acid.

4. Concentration of hydrogen ions in sulphuric acid is double

than that in hydrochloric acid.

1

1

1

1

4

Total 20

Volume of

gas / cm3

Time / min

Exp II

Exp I

2


11


Mark

9(a) P1: Magnesium atom undergoes oxidation

P2: oxidation number increases from 0 to 2+

P3: Copper (II) ion undergoes reduction

P4: oxidation number decreases from +2 to 0

P5: The reaction involving oxidation and reduction

1

1

1

1

1

MAX

4

(b) Experiment I

L can reduce copper(II) oxide// L can react with copper(II) oxide

L is more reactive than copper.

Experiment II

M can reduce copper(II) oxide//M can react with copper(II)

oxide

M is more reactive than copper.

Experiment III

M cannot reduce L oxide // M cannot react with L oxide.

M is less reactive than L//L is more reactive than M.

The arrangement in order of increasing reactivity toward oxygen is Cu,

M and L.

1

1

1

1

1

1

Max

5

1

6

(c)

Procedure :

P1. Pour 2 cm3 of potassium bromide solution into a test tube.

P2. Add 2 cm3 of chlorine water to the test tube and shake the mixture.

P3. Add 2 cm3 of 1,1,1 trichloroethane to the test tube and shake the

mixture.

P4. Record the observation

P5. Repeat steps 1-4 using another halogens and halide solution.

.

1

1

1

1

1


12

Result :

Chlorine water Bromine water Iodine water

Potassium

chloride

X X

Potassium

bromide X

Potassium

iodide

Ionic equation:

1. Cl2 + 2Br- 2Cl

- + Br2

2. Cl2 + 2I- 2Cl

- + I2

3. Br2 + 2I- 2Br

- + I2

1

1

1

1

1

10

20


13


Mark

10(a)

Precipitation / double decomposition reaction

Barium nitrate solution/barium chloride solution

[Any sulphate solution]

Example: sodium sulphate, potasium sulphate, sulphuric

acid

Reject : Lead(II) sulphate, calcium sulphate

Ba2+

+ SO42 BaSO4

1

1

1

1

4

10(b)(i) Cation : Iron(II) ion / Fe

2+

Anion: Chloride ion / Cl

1

1

2

10(b)(ii)

Test for NO3

P1: Add 2 cm3

of dilute sulphuric acid into the test tube follow

by 2 cm3 of iron(II) sulphate solution.

P2: Add a few drops of concentrated sulphuric acid

P3: carefully and slowly along the side of slanting test tube

into the mixture.

P2: A brown ring is formed.

1

1

1

1

4

10(c)

Procedure:

P1. Add zinc nitrate solution to sodium carbonate solution

in a beaker.

P2. Stir the mixture.

P3. Filter the white precipitate/solid zinc carbonate formed.

P4. Add zinc carbonate to sulphuric acid in a beaker until

some zinc carbonate solid no longer dissolve.

P5. Filter the mixture.

P6. Transfer the filtrate to a evaporating dish.

P7. Heat the filtrate(zinc sulphate solution) until saturated//

Heat the filtrate to about one-third (1/3) of its initial

volume

P8. Allow the saturated solution to cool at room temperature.

P9. Filter the crystals formed.

P10. Dry the crystals by pressing it between two sheets of

filter papers.

1

1

1

1

1

1

1

1

1

1

10

Total 20


Spm Trial 2012 Chemistry a SBP

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