[edu.joshuatly.com] trial kelantan stpm 2012 chemistry [94662c28].pdf

7/27/2019 [edu.joshuatly.com] Trial Kelantan STPM 2012 Chemistry [94662C28].pdf

1/42

JABATAN PELAJARAN KELANTAN

TRIAL EXAMINATION

2012

CHEMISTRY (KIMIA)

SIJIL TINGGI PERSEKOLAHAN MALAYSIA(MALAYSIA HIGHER SCHOOL EDUCATION)

PAPER 1 (KERTAS 1)MULTIPLE-CHOICE (ANEKA PILIHAN)

One hour and forty-five minutes (Satu jam empat puluh lima minit)

Instructions to candidates :

DO NOT OPEN THIS BOOKLET UNTIL YOU TOLD TO DO SO

There are fifty questions in this paper. For each question, four suggested answers are

given. Choose one correct answer and indicate it on the multiple-choice answer sheet

provided.

Read the instructions on the multiple-choice answer sheet very carefully.

Answerall questions. Marks will not be deducted for wrong answers.

Arahan kepada calon :

JANGAN BUKA BUKU SOALAN INI SEHINGGA ANDA DIBENARKAN

BERBUAT DEMIKIAN

Ada lima puluh soalan dalam kertas ini. Bagi setiap soalan, empat cadangan

jawapan diberikan. Pilih satu jawapan yang betul dan tandakan jawapan itu pada

helaian jawapan aneka pilihan yang dibekalkan.

Baca arahan pada helaian jawapan aneka pilihan itu dengan teliti.

Jawab semua soalan. Markah tidak akan ditolak bagi jawapan yang salah.

This question paper consists of 18 printed pages

(Kertas soalan ini terdiri daripada 18 halaman bercetak)

962/1

http://edu.joshuatly.com/http://fb.me/edu.joshuatly


2/42

962/1 [Turn over* This question paper is CONFIDENTIAL until the examination is over. CONFIDENTIAL*

2

Section A

Four suggested answers labeledA, B, C, andD are given for each question. Chooseone correct answer.

1 The unit cell of an elementMis shown below:

Given the volume of the unit cell is cm and the molar volume ofMatoms is bcm, what the value for the Avogadro constant?

A

B

14

C

12

D

4

2 Copper is usually obtained as a mixture of 69.09% Cu isotope and 30.91% Cuisotope. If the masses of 63Cu and 65Cu isotopes are 62.93 amu and 64.93 amurespectively, what is the relative atomic mass of copper?A 63.62

B 63.55

C 63.93

D 64.31



3/42


3

3 What is the maximum number of electrons in third shell of an atom?

A 2

B 8

C 18D 32

5 Which of the following properties show a gradual increasing trend withincreasing proton number for the elements Sc and Cu?A Density

B Boiling point

C Melting point

D First ionisation energy

6 Ar, K+, and Ca + are isoelectronic. The order of increasing radii is

A Ca2+ < K+ < Ar

B Ca2+ < Ar < K+

C Ar < Ca2+


4/42


4

7 Which element possesses the strongest metallic bond?

A Magnesium

B Calcium

C SodiumD Lithium

8 XH3 is a gaseous hydride of an element in Group 15 of Periodic Table. Which ofthe following shapes is most appropriate for the hydride molecule?A V-shaped

B Trigonal pyramid

C Plane trigonal

D Tetrahedral

9 Which of the following molecules is polar?A SF6

B BCl3

C SnCl4

D

CH3Cl

10 Magnesium metal is a good conductor of electricity. Which of the followingstatements is true of the metal?A The 3s orbital forms the valence and conduction band

B The electrons in 3s and 3p orbitals are delocalised

C The energy gap between the valence band and the conduction band is large

D Its conductivity is lower than silicon when the temperature increase



5/42


5

11 The thermal decomposition of hydrogen iodide is a second order reaction.

Which of the following graphs is correct for this reaction?

A

B

C

D

2 HI(g)H2(g) + I2(g)

Time

[HI]

Time

Rate

[HI]2

lg [HI]

Time



6/42


6

12 The equilibrium constant, Kc, for the reaction

is given byA C

B D

13 In the Contact process, sulphur dioxide is converted into sulphur trioxideaccording to the following equation:

His negative

Which of the following sets of conditions at equilibrium would give the highestyield of sulphur trioxide?

Temperature Pressure Catalyst

A High High Present

B Low High None

C High Low None

D High High None

14 The solubility product of silver chloride is 1.0 10 - mol dm- . What mass ofsilver chloride will dissolve in 1 dm3 of a solution of sodium chloride with aconcentration of 0.10 mol dm-3?A 1.0 10-14 mol dm-3

B 1.0 10-10 mol dm-3

C 1.0 10-9 mol dm-3

D 1.0 10-5 mol dm-3

2NH3(g) + 3CuO(s) 3Cu(s) + N2(g) + 3H2O(g)

[Cu]3[N2][H2O]3

[NH3]2[CuO]3

[N2] [H2O]3

[NH3]2

[N2][H2O]

[NH3]

3[N2] [H2O]

2 [NH3]

2SO2(g) + O2(g) 2SO3(g);



7/42


7

15 Which of the following species could behave as an acid and a base according toBronsted- Lowry theory?A HCO3-

B CO32-

C OH-

D HCl

16 The partition coefficient of substanceX between ether and water is 8.0 at roomtemperature. An aqueous solution containing 5.0 g ofXin 100cm3 of water isextracted with 100cm3 of ether. What is the maximum mass ofXthat can beextracted into the ether layer?A 0.35 g

B 2.34 g

C 4.44 g

D 3.98 g

17 The chromatogram below is obtained from thin layer chromatography of a sampleof amino acid P, Q, R and S.

Base on the Rf value in the table below, deduce the amino acids present in thesample.

Amino acidRf

valueP 0.16Q 0.32R 0.68S 0.84

A P and S

B Q and R

C P and Q

D P and R

8.4 cm

6.8 cmSolvent front

Base line

10 cm



8/42


8

18 Consider the half-cells below:

Cu+ + e- Cu E = +0.52 VCu2+ + e- Cu+ E = +0.52 V

What is the E for the reaction :2Cu+Cu2+ + Cu

A -0.68V C +0.36V

B -0.36V D 0.00V

19 Which of the following is not true for the Daniel cell?

A The e.m.f is 1.10V

B Its anode has a negative charge.

C It function as an electrolysis cell

D Electrons flow from the zinc electrode to the copper electrode

20 Which of the following compounds is expected to have the most negative latticeenergy?A LiF

B LiBr

C NaCl

D NaF

21 Which of the following processes involves the enthalpy of formation?

A

H2(g) + O(g)

H2O(l)B 2CO(g) + O2(g)2CO2(g)

C Na+(g) + Cl- (g) NaCl(s)

D 2C(s) + 3H2(g) + O2(g)C2H5OH(l)



9/42


9

23 Which of the following elements in the same period of the Periodic Table has thehighest boiling point?A Sodium

B Sulphur

C Aluminium

D Magnesium

24 Which of the following shows the changes in properties of oxides of Group 14elements (carbon to lead) in the Periodic Table?A Acidic basic neutral

B Acidic neutral basic

C Acidic amphoteric basic

D Basic amphoteric acidic

25 Which of the following statements about Group 14 elements (carbon to lead) ofthe Periodic Table is true?A Only CCl4 is hydrolysed by water.

B Only oxides of tin and lead are amphoteric.

C All oxide of elements give oxygen gas when heated strongly.D +2 oxidation state of elements becomes more stable when moving down the

group.

22 Which of the following is the correct physical property of elements across theThird Period from sodium to chlorine in the Periodic Table?A Size of atoms increases.

B Melting point decreases.C Electronegativity decreases.

D First ionization energy increases.



10/42


10

26 Which statement about the properties of the tetrachlorides of Group 14, CCl4 toSnCl4, is correct?A They are all polar molecules.

B Their melting points increase down the group.

C Their boiling points decrease down the group.

D Tin (IV) chloride is the only ionic tetrachloride.

27 Nitrogen is very non-reactive at low temperatures because the gas

A has half-filledp orbitals.

B has high atomisation energy.C exists as diatomic molecules.

D has a stable electron configuration.

28 Which of the following statements is not true about halogens?

A Solubility in water decreases.

B They exist as diatomic molecules.

C Reactivity with hydrogen increases down the group.D They become darker in colour moving down the group.

29 Which of the following elements in the first series of transition elements does notshow general characteristics of a transition element?A Copper

B Nickel

C ScandiumD Vanadium



11/42


11

30 An organic compound has the structure

Which of the following is not true regarding the compound?A It exihibits geometrical isomerism

B It exihibits optical isomerism

C It decolorises acidified potassium manganate (VII)D It is insoluble in water

31 Benzene reacts with a mixture of concentrated nitric acid and concentrated sulphuricacid to produce nitrobenzene according to the equation:

C6H6 + HNO3 C6H5NO2 + H2O

What is the function of sulphuric acid in the above reaction?

A To protonate the nitric acidB To eliminate the water produced

C To prevent di-substitution from occurring

D To prevent oxidation of benzene by nitric acid

32 The reaction mechanism between chlorine and methane is shown below:

Cl2 2Cl (i)

CH4 + Cl CH3 +HCl (ii)

CH3 + Cl2 CH3Cl + Cl (iii)

Which of the following is not true regarding the reaction?A Reaction (i) requires ultra-violet light

BThe reaction can occur in the dark if the mixture is heated with benzoyl

peroxideC CH3Cl is the only product formed

D A little C2H6 is also formed in the reaction

H2SO4

CH3

C

CH3 CH2



12/42


12

33 The scheme below shows the production of compound Z from 2-propanol.

Which of the following areX, YandZ?

X Y Z

A Br2

B Br2

C PBr3

D PBr3

CH3CHOH

CH3

CH3CHBr

CH3

CH3

CH3CHMgBr

X

Y ZH2O/H+

CrO3 Mg

CH3C=O

CH3

CH3

CH3CH C

CH3

CH3

OH

CH3C=O

CH3 CH3

CH3CHCH2CH2CH2OH

CH3C=O

CH3

CH3C=O

CH3

CH3

CH3CH C

CH3

CH3

OH

CH3CH3CH C

CH3

CH3OH



13/42


13

35 When a compound P which does not react with acidified solution of potassiumdichromate (VI), is heated with aluminium oxide, compound Q is produced. Thecompound Q can decolourise bromine water. IfQ is treated with hydrogen bromide,2-bromo-2-methylpropane is produced.

CompoundPcould be

A butan-2-one

B propan-2-ol

C butan-2-ol

D 2-methylpropan-2-ol

36 Which of the following compounds could be the main product when ethanoic acid istreated with lithium tetrahydridoaluminate (III) ?

A CH3CH3

B CH2=CH2

C CH3CHO

D CH3CH2OH

34 A compound Z shows the following properties:

(i) Reacts with sodium to give a combustible gas(ii) Reacts with benzoyl chloride to give a precipitate

(iii) Reacts with aqueous solution of sodium hydroxide to give a saltCompound Z could be

A

B

C

D

OH

OH

CH2OH

CHO



14/42


14

37 Acarol is sold as insecticides for fruits and vegetables.

AcarolThe last step in its manufacture is esterification. Which alcohol is used to make theabove ester?

A Di(4-bromophenyl)methanol

B Methanol

C Propan-1-ol

D Propan-2-ol

38 The correct order of increasing basicity of ammonia, ethylamine and phenylamine isA ammonia < ethylamine < phenylamine

B

phenylamine < ammonia < ethylamineC ethylamine < phenylamine < ammonia

D phenylamine < ethylamine < ammonia

39Which of the following statements about 2-aminopropanoic acid and aminoethanoicacid is not true?A both are optically active

B Both form a salt with mineral acid

C Both react with nitric (III) acid

D Both form zwitterions in aqueous solutions

C

Br

C O CH

Br

OH CH3

CH3

O



15/42


15

Section B

For each of the questions in this section one or more of the three numbered

statements 1 to 3 may be correct. Decide whether each of the statements is or is not

correct. The responses A to D should be selected on the basis of the following.

40 Which of the following pairs are monomers of a condensation polymer?

A CH3O2CCCH2CH2COOCH3 and CH2=CHCH=CH2

Band H2N(CH2)NH2

C O=CHCH2CH2CH=O and

D and H2NCH2CH2NH2

41 Which of the following statements are correct for the elements in the Periodic

Table?1 The elements are arranged in the order of increasing proton number.

2 The atomic radii increases down a group.

3 Electronegativity increase across a period.

42 Which of the following are true of a first order reaction?1 The rate constant is dependent on the temperature.

2 The half-life is independent of the initial reactant concentration

3 The units of the rate constant is time-1.

A B C D

1 onlyis correct

1 and 2are correct

2 and 3 onlyare correct.

1 , 2, and 3are correct.

OHHO

CH3CH3

COOHHOOC



16/42


16

43 In the Nernst equation,

Ecell = Eocell +

ln

Which of the following quantities can have both positive and negative values?

1[Oxidation form]

[reduced form]2 E

3 T

44 Which of the following properties of ammonia can be explained in terms ofhydrogen bonding?1 It is very soluble in water.

2 It is a base.

3 The liquid form contains the ions NH4+ and NH2-

45 Why are most catalysts transition elements or their compounds?1 They have a high charge density.

2 They show variable oxidation states.3 They have available dorbitals for bonding.

46 Ethene and ethane can be differentiated by using1 acidified KMnO4

2 bromine in the absence of light

3 concentrated sulphuric (VI) acid

A B C D

1 onlyis correct

1 and 2are correct



ln



17/42


17

48 Oxidation of pentane-2-ol produces compoundX. Xis expected to1 give an orange precipitate with 2,4-dinitrophenylhydrazine

2 give a negative reaction with Tollens reagent3 give a yellow precipitate with alkaline iodine

A B C D

1 onlyis correct

1 and 2are correct



47 One mole of organic compound, X, reacts with two moles of sodium hydroxideon heating.Xcould be,

1

2

3

CHCl2

Cl

Cl

CH2Cl Cl



18/42


18

49 Z, C2H5NO2, reacts with nitrous acid to release nitrogen gas. 10cm of a solutioncontaining 0.75g dm-3 ofZrequires 10cm3 of 0.01 mol dm-3 sodium hydroxidefor complete reaction. Which of the following is/ are true regardingZ?1 It is an amino acid

2 It contains one COOH group in its molecule3 It is an amide

50 Clearfilm is manufactured from a polymer made by copolymerizing

1

2

3

END OF QUESTION PAPER

CH2=CHCl and CH2=CCl2

--CHClCH2CCl2--

--CH2CHClCCl2--

--CCl2CCl2CH2CHCl--



19/42

CONFIDENTIAL* 962/2

This question paper is CONFIDENTIAL until the examination is over. CONFIDENTIAL*

2

SECTION AAnswerall the questions in this section.

1(a) Nitrogen is used in the packing of junk food to keep the food fresher for a longerperiod.

(i) Write the electronic configuration of the nitrogen atoms. [1 mark]

.

(ii) Nitrogen can form the NCl3 molecule only, but phosphorous can form both the PCl3as well as PCl5 molecule. Draw the Lewis diagram for NCl3 and PCl5 and Predict the polarity

NCl3 and PCl5. [4 marks]

(iii) Show and label the overlapping orbital of N2H4. [3 marks]



20/42

CONFIDENTIAL* 962/2


3

(b) The diagram below shows the four electron transitions in the hydrogen atom.(i) Base on the energy level diagram, sketch the line spectrum formed

from these transition. [2 marks]

2 Some standard electrode potentials are shown below.

Half Reaction Eo/V

Ag+ + Ag + 0.80

Cl2 + Cl- + 1.36

Cu2+ + 2 Cu + 0.34

Fe3+ + Fe2+ + 0.77

I2 + I- + 0.54

(a) The diagram below shows an incomplete cell consisting of Cu/Cu2+ and Ag/Ag+

half-cells under standard conditions.

Energy

n=5n=4

n=3

n=2

n=1



21/42

CONFIDENTIAL* 962/2


4

(i) Complete and label the diagram to show how the cell potential of this cellcould be measured. [2 marks]

(ii) On the diagram, show the direction of electronflow in the circuit. [1 mark]

(iii) Write the cell diagram for the above set-up. [1 mark]

...............................................................................................................

(iv) Write the overall cell reaction. [1 mark]

.................................................................................................................(v) Calculate the standard cell potential. [1 mark]

(vi) Calculate the cell potential if the solution in the right beaker is replaced with0.10 mol dm-3 aqueous silver nitrate, other factors remaining unchanged. [ 2 marks]

(b) Chlorine will oxidise Fe2+ to Fe3+ but iodine will not. Explain why using the electrodepotential data. [2 marks]

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................



22/42

CONFIDENTIAL* 962/2


5

3(a) (i) What do you understand by the term complex ion? [2 marks]

(ii) 1,2-ethenediamine is a chelating ligand. Explain the term chelating ligand.[1 mark]

.

(b) A series of experiments were carried out on an aqueous solution of copper(II) sulphate.

Experiment ObservationAqueous sodium hydroxide is added tocopper(II) sulphate solution A blue precipitate is formed

Aqueous ammonia is added tocopper(II) sulphate solution until inexcess

The blue precipitate dissolves and a darkblue solution is obtained

(i) Write the formula of all the complex ions in the experiments [2 marks]

(ii) Arrange the ligands in order of increasing strength with respect to copper(II). Explainyour answer. [2 marks]

..

(iii) Explain why transition element complex are often coloured , whereascompounds of other metals are usually white. [3 marks]

.

.



23/42

CONFIDENTIAL* 962/2


6

4(a) Aspartame is an artificial sweetener which is 180 times sweeter than sugar.The structural formula ofaspartame is

H2N CH- CO NH CH COO CH3| |

CH2 CH2| |COOH

(i) Name four different functional groups in the molecule ofaspartame.[4 marks]

(ii) Identify two of the functional groups which contribute to its solubility in

water. Give reasons for your answer. [2 marks]

(b) Aspartame can be hydrolyses into its constituent parts under certain conditions.

(i) Suggest the reagent and condition for hydrolysis. [1 mark]

....

(ii) Draw the structural formulae of all organic molecules obtained by hydrolysis aspartame. [3 marks]



24/42

CONFIDENTIAL* 962/2


7

SECTION BAnswerany fourquestions in this section.

5(a) Krypton is used to fill fluorescent lights and photo graphic flash lamps.

(i) Use the following data to sketch a phase diagram for krypton [4 marks]

(ii) What is meant by the term triple point? [1 mark]

(iii) What are the physical states of krypton under P = 5.3 atm , T = -153C and

P= 65 atm , T = 250C [2 marks]

(iv) Can a sample of gaseous krypton at room temperature be liquefied by raising

its pressure? Explain why? [2 marks]

(b) At 101 kPa, the boiling points of pure ethanol and water are 78.5C and 100.0Crespectively. A solution of ethanol and water forms an azeotropic mixture with a boiling

point of 78.2C. The percentage by mass of ethanol in the mixture is 96.0% ethanol.Theboiling point-composition curve for the ethanol-water mixture is shown below.

(i) This mixture does not obey Raoult law. State the type of deviation andexplain. [3 marks]

(ii) Briefly explain how pure ethanol can be obtained from a 70% ethanol mixture.[3 marks]

Pressure/atm Temperature/C

Triple point 0.175 -169

Critical point 54 -63

Melting point 1 -156.6

Boiling point 1 -152.3

Temperature/oC

0% 100%

78.5

100

96%

78.2

composition



25/42

CONFIDENTIAL* 962/2


8

6(a) 1.00 g of solid potassium hydroxide was dropped into 50.0 cm3 (50.0 g) of aqueoushydrogen chloride (slightly in excess) contained in a polystyrene cup. A temperature changefrom 30.0oC to 40.0oC was recorded with a thermometer in the solution.(The specific heat capacity of the solution is 4.0 J K-1 g-1).

(i) Define the heat of neutralization. [2 mark](ii) Write a balance equation for the above equation. [1 mark]

(iii) From the experimental data provided, calculate H for the reaction.[3 marks]

(iv) Give one important reason why it is preferable to use a polystyrene cup

instead of a glass beaker. [1 mark]

(v) Why should the solution stirred during the reaction. [1 mark]

(b) Octane, C8H18 is used as fuel.(i) Define the heat of combustion with related to octane . [1 mark]

(ii) Write a balance equation for the combustion of octane in excess oxygen.[1 mark]

(iii) Calculate the standard enthalpy of combustion of octane by using thefollowing information.

Hf of CO2 -394 kJ mol-1

Hf of H20 -286 kJ mol-1

Hfof C8H18 -250 kJ mol-1 [3 marks]

(iv) How is the knowledge of standard enthalpy of combustion useful to a chemistother than that of as fuel? [2 marks]



26/42

CONFIDENTIAL* 962/2


9

7(a) The table below gives the melting point for each of the Period 3 elements Na to Ar.

(i) Describe and explain the difference between the electrical conductivities of theelements aluminium, silicon and phosphorus. [4 marks]

(ii) When aluminium combines with chlorine, it results in the formation ofaluminium chloride. Aluminium chloride can further react with chloride ions asshown by the equation below.

AlCl3 + Cl AlCl4

Explain how the bond between aluminium chloride and the chloride ion is

formed. [3 marks]

(b) The table below shows the elements in group II of the periodic table.

ElementBerylliumMagnesiumCalciumStrontiumBarium

(i) State and explain the differences in bonding between beryllium chloride andmagnesium chloride. [3 marks]

(ii) Sulphates of the Group II elements have different solubilities. State andexplain the trend in solubilities. [2 marks ]

(iii) A student on a field trip investigates some disused mining pools which havebeen flooded for some time. The presence of barium ions in the water is to bedemonstrated by precipitating barium(II) sulphate. The solubility of barium(II)

sulphate in water at 25

o

C is 1.05 x 10

-5

mol dm

-3

. Calculate its solubility productand state one use that depends upon this insolubility. [3 marks]



27/42

CONFIDENTIAL* 962/2


10

8 Ammonia is one of the best-known compounds. It is prepared industrially fromnitrogen and hydrogen by the Haber process. The equation for the main reaction in the Haber

process isN2(g) + 3H2(g) 2NH3(g) H = negative

The table below gives information about the percentage yields of ammonia obtained in the

Haber process under different conditions.

Pressure/atmTemperature/C

200 300 400 500

10

100

200

300

400600

50.7

81.7

89.1

89.9

94.695.4

14.7

52.5

66.7

71.1

79.784.2

3.9

25.2

38.8

47.1

55.465.2

1.2

10.6

18.3

24.4

31.942.3

(a) (i) From the table, state the conditions that gives the higher yield of ammonia.[2 marks]

(ii) State a suitable catalyst .[1 mark]

(b)Ammonia can be oxidised by air to form nitrogen oxide.4NH3(g) + 5O2(g) 4NO(g) + 6H2O(g) H= -909kJmol-1

This reaction forms the first stage in the manufacture of nitric acid from ammonia.Using Le Chatelier s principle state and explain the change in equilibrium yieldof nitrogen oxide caused by:

(i) Increasing the pressure at constant temperature [3 marks](ii)Increasing the temperature at constant pressure [3 marks](iii)The industrial process is operated at a temperature of about 900C. Suggest a

reason for this temperature. [2 marks]

(c) An aqueous solution of nickel(II) chloride reacts with aqueous ammonia to form aprecipitate X. The precipitate X dissolves in excess aqueous ammonia to give asolution Y. State the colours of X and Y and also write the chemical formula of each.

[4 marks]



28/42

CONFIDENTIAL* 962/2


11

9(a) An amount of 0.01 mole of a hydrocarbon is burnt in excess oxygen. The products ofthe combustion are passed through anhydrous calcium chloride and then through potassiumhydroxide solution. The masses of anhydrous calcium chloride and potassium hydroxidesolution increase by 0.72 g and 1.76 g respectively.

(i) Determine the empirical formula of the hydrocarbon. [4marks](ii) Determine the relative molecular mass of the hydrocarbon and hence its

molecular formula. [4marks]

(b) Draw the structure of the major product of each of the following reactions.

(i) + NH3 ethanol [1 marks]

(ii) (CH3)2CBr2 + NaOH [1 marks]

(iii) [1 marks]

(c) The molecular structure of compounds Tis given below.

Whatare the organic products expected when Tis reacted with each of the followingreagents ?(i) H2 / Pt [1 marks](ii) LiAlH4 , followed by H3O+ [1 marks](iii) I2 / NaOH [2 marks]

Br

CHO(i) CH3CH2MgBr(ii) H3O+

O

CH3C CH2 =O



29/42

CONFIDENTIAL* 962/2


12

10(a) Natural rubber is cis-poly(2-methyl-1,3-butadiene). Physical properties are alteredafter vulcanisation process.

(i) Draw a repeating unit for the above polymer. [1 mark]

(ii) What characteristic must be present in the molecule of the polymer so that thevulcanisation process can be carried out? [1 mark]

(iii) State two changes in the physical properties of natural rubber after thevulcanisation. [2 marks]

(iv) If an excess of the vulcanising agent is added during the vulcanisation process,what would be the change in the physical properties of the natural rubber ? [1 mark]

(v) State the vulcanising agent and draw the structure of vulcanised rubber.[2 marks]

(vi) Natural rubber is a type ofelastomer. What would you understand by the termelastomer?

[1 mark]

(b) The possible mechanism for hydrolysis of 3-bromo-3-methylhexane by hydroxide ion,OH- is as follows:

slow

C3H

7- C(OH)(CH

3)-C

2H

5

(i) Write the rate equation for the above mechanism. [1 mark]

(ii) What will happen to the rate of reaction if OH- is replaced by CN- ?Explain your answer. [2 marks]

(iii) Name the above mechanism. [1 mark]

(iv) 3-bromo-3-methylhexane shows stereoisomerism. Name the type of isomerismand draw all the structural formulae of this isomers. [3 marks]

C3H7- C(Br)(CH3)-C2H5

C3H7- C(CH3)-C2H5 + OH-

+

C3H7- C(CH3)-C2H5+

fast



30/42

STPM TRIAL 2012

Suggested Answer

Chemistry 962/1

1 D 11 C 21 D 31 A 41 D

2 B 12 B 22 D 32 C 42 D

3 C 13 B 23 C 33 D 43 B

4 B 14 C 24 C 34 B 44 A

5 A 15 A 25 D 35 D 45 C

6 A 16 C 26 B 36 D 46 B

7 B 17 A 27 B 37 D 47 A

8 B 18 C 28 C 38 B 48 D

9 D 19 C 29 C 39 A 49 B

10 A 20 A 30 A 40 D 50 A



31/42

CONFIDENTIAL* 962/21

CHEMISTRY MARKING SCHEMESTPM TRIAL 2012

1 (a) (i) N : 1s 2s 2p [1](ii)

NCl3 PCl5NCl3 : Polar molecule PCl5: non-polar molecule

[1]+[1]

[1]+[1]

(iii) Overlapping orbital of N2H4

Label the hybrid orbitalShow overlappingLabel sigma() bond

[1][1][1]

(b) (i)

[1]+[1]

TOTAL MARKS 10

Increasing frequency

N N

H

H

H

H

P

x

x

x

x x

ClCl

Cl Cl

Cl

P

x

x

x

x x

NCl

Cl

Cl



32/42


2 (a) (i)[1][1]

(ii) Direction of electron flow from Cu(s) to Ag(s) (must be in/close to wire) [1]

(iii) Cu(s)Cu2+(aq)// Ag+(aq)Ag(s) [1]

(iv) Cu(s) + 2Ag+(aq) Cu2+(aq) + 2Ag(s) [1]

(v) Eocell = ( 0.34) + ( +0.80) or= + 0.46 V [1]

(vi) Nernst Equation

2

2

][

][log

2

059.0

Ag

CuEE ocellcell

or

V40.0

10.0

00.1log

2

059.0)46.0(

2

[1]

[1]

(c) Standard electrode potential for chlorine is more positive than Fe +therefore it is a better oxidising agent than Fe3+ (do not accept Eo islarger or smaller)Standard electrode potential for iodine is less positive than Fe3+therefore it is a poorer oxidising agent than Fe3+.(Accept release of electrons/equilibrium arguments)

Or calculation

[1]

[1]

TOTAL MARKS 10http://edu.joshuatly.com/http://fb.me/edu.joshuatly


33/42


3 (a) (i) An ion which formed when a metallic ion is bonded to a group of ligandby dative bonds

[1][1]

(ii) Ligand that can donate more than one lone pair electrons [1]

(b) (i)[Cu(H2O)6]2+ ; [Cu(H2O)4(OH)2] ; [Cu(NH3)4]2+

3 corrects2 corrects

[2][1]

(ii) H2O < OH- < NH3

A stronger ligand is able to displace a weaker ligand from the complexion

[1]

[1]

(iii) Transition metal ions have incomplete 3d-subshell / d1 to d9d-d electronic transition is possiblenon transition metal / other metal have either completely filled 3d orbitals orno 3d electron or no d-d electronic transition

[1][1]

[1]

TOTAL MARKS 10



34/42


4 (a) (i) Carboxyl, amino, ester and amide [4]

(ii) Amine and carboxylic acid.

This amino acid can exist as zwitterionsAttraction between this ion with polar water molecules is responsible forit solubility

[1]

[1]

(b) (i) Heat with dilute sulphuric acid / H2SO4 / H+ [1]

(ii) [1]

+ _H3N CH COO

|CH2|

[1]

[1]

TOTAL MARKS 10

OH|

H - C - H|

H

+ _H3N CH COO

|CH2|

COOH



35/42


P/atm

T/C

Liquid

54Critical point

0.175 Triplepoint

-169 -63

5 (a) (i)

Correct x-axis , y-axis and label

Correct curve

All point labelAll phases label

[1][1]

[1][1]

(ii) Conditions of temperature and pressure under which a substance canexist in the solid, liquid and gas in equilibrium [1]

(iii) LiquidGas

[1][1]

(iii) CannotBecause room temperature is above critical temperature

[1][1]

(b) (i) Positive deviation

Because hydrogen bonds /attractive forces between ethanol and watermolecules are weaker than those between the pure molecules

Hence the ethanol and water molecules easily escape from this mixture.ortotal vapour pressure is higher than predicted

[1]

[1]

[1]

(ii) Fractional distillation.

Distillate is an azeotropic mixture / 96% ethanol.

Pure ethanol can be obtained by adding anhydrous calcium oxide toremove water.(any other drying agent)

[1]

[1]

[1]

15

Solid

Gas



36/42


6 (a) (i) The standard enthalpy of neutralization, Hneut is the enthalpychange when one mole of hydrogen ions, H+(aq), reacts with onemole of hydroxide ions, OH-(aq),to form one mole of water under standard condition.

[1][1]

(ii) KOH(aq) + HCl(aq) KCl(s) + H2O(l) [1]

(iii) Molar mass of KOH = 39.1 + 16.0 + 1.0 = 56.1

Amount of KOH used =

= 0.0179 molOr = 1.79 x 10-2 mol

Heat evolved = mcOr = 50.0 x 4.0 x (40.0 -30.0)

= 2000 J or= 2.00 kJ

H = -

Or = -112 kJ mol-1

[1]

[1]

[1]

(iv) Polystyrene cup is a good heat insulator and has a low heat capacity.

[1]

(v) Stirring speeds up dissolving and so minimize heat loss during thedissolving process by reducing the duration of the experiment.

OrIt also provides even distribution of temperature. [1]

(b) (i) The standard enthalpy of combustion is the heat released when onemole of octane is completely burned in excess oxygen understandard condition. [1]

(ii) 2C8H18(l) + 25O2(g) 16CO2(g) + 18H2O [1]

(iii) 2C8H18(l) + 25O2(g) 16CO2(g) + 18H2O

Hf : 2(-250) 0 16(-394) 18(-286)

or H = [18Hf(H2O) + 16Hf(CO2)] [2Hf(C8H18) +25Hf(O2)]

= [18(-286) + 16(-394)] [2(-250) + 25(0)]= -10952 kJ mol-1= -1.09 x 104 kJ mol-1

[1]

[1]

[1]

(iv) When storing chemical substances with high enthalpy of combustion,they must be protected from sunlight or sources of heat.

Or to present explosion

[1]

[1]TOTAL MARKS 15



37/42


7 a) (i)Aluminium is a good conductor.

Silicon and phosphorus are non-conductors.

Aluminium has metallic bond with delocalized electrons.

Silicon & phosphorus have localized electrons /do not havedelocalized electrons.

[1]

[1]

[1]

[1]

(ii) Dative bond

Electron pair/lone pair donated from Cl- to Al/AlCl3

Diagram

[1]

[1]

[1]

b) (i) Beryllium chloride is covalent.

Magnesium chloride is ionic.

The beryllium atom is much smaller than the magnesium atom,more difficult for it to transfer electrons to the chlorine atoms,instead it shares the electrons

[1]

[1]

[1]

(ii) Solubility of the group 2 sulphates decreases down the group fromberyllium to barium.

Going down the group,

lattice enthalpy decreases slowly (since the sulphate ion is large )but hydration enthalpy shows a larger decrease

hence the enthalpy of solution becomes more positive.

[1]

[1]

[1]

(iii) BaSO4(s) Ba +(aq) + SO4 -(aq) (1)

Each mole of barium sulphate dissolves to give 1 mole of bariumions and 1 mole of sulphate ions in solution.

[Ba2+

] = 1.05 x 10-5

mol dm-3

[SO42-] = 1.05 x 10-5 mol dm-3Ksp = [Ba2+][SO42-]

[1]

[1]http://edu.joshuatly.com/http://fb.me/edu.joshuatly


38/42


= (1.05 x 10-5)(1.05 x 10-5) or= 1.10 x 10-10 mol2 dm-6

Use:

contrast medium used for X-ray imaging of the intestines/gastrointestinal tract ORwhite pigment for paints OR

component of oil well drilling fluid

[1]

[1]TOTAL MARKS 15

8 a) (i) High pressure or 600 atm

Low temperature or 200oC

[1]

[1]

(ii) Iron filling [1]

b) (i) Yield or NO decrease

No of gas molecules increase (9 to 10)

The equilibrium shift to the left / backward

[1]

[1]

[1]

(ii) yield is reduced/ decrease

Forward reaction is exorthermic so

the equilibrium to the left

[1]

[1]

[1]

(iii) If temperature is reduced the yield is increased.

At lower temperature the rate of reaction will be very slow.

[1]

[1]

c) X Green, Ni(OH)2

Y Blue, Ni(NH3)62+

[1+1]

[1+1]

TOTAL MARKS 15



39/42


9 (a) (i) CxHy + [ x + y/4]O2 x CO2 + y/2 H2O

anhydrous CaCl2 absorbs water and KOH absorbs carbon dioxide-themass of water is 0.72 g and the mass of carbon dioxide is 1.76 g

Mass of C =

OR

= 0.48 g

The mass of C is 0.48 g.

Mass of H =

OR

= 0.08 g

The mass of H is 0.08 g.

Element C H

Mass 0.48 0.08

Number of moles0.4812.0

=0.04

0.081.0

=0.08

Mole ratio1 2

Empirical formula is CH2

[1]

[1]

[1]

[1]

[1]

(ii) The mass of hydrocarbon = mass of C + mass of H= 0.48 + 0.08= 0.56 g

Relative molecular mass = mass

mol= 0.56 OR

0.01= 56

(CH2)n = 56or 14n = 56or n = 4

Molecular formula is C4H8

[1]

[1]

[1]

[1]



40/42


(b) (i)

(ii)

(iii)

(CH3)2C(OH)2 (CH3)2C=O

[1]

[1+1]

[1]

(c) (i)

(ii)

(iii)

OH|CH3CCH2-

|H

OH|

CH3CCH2- --OH|

H

O

+NaO- CCH2- =O and CHI3

[1]

[1]

[1+1]

TOTAL MARKSMAX

1715

NH2

CH(OH)CH2CH3

OH



41/42


10 (a) (i)

[1]

(ii)

(iii)

(iv)

(v)

(vi)

C= C or double bond

hardermore elastic

less sticky[ any two ]

hard and brittle (both)

sulphur

Elastomer is polymer that stretches when pulled and return to theirlength or shape when the force is released. /elastic

[1]

[1]+[1]

[1]

[1]

[1]

[1]

(b)(i)

(ii)

(iii)

Rate = k [ C3H7-C(Br)(CH3)-C2H5 ]

constant or no change

because OH- ion does not involve in the rate of determining stepOR only reactant (3-bromo-3-methylhexane) affected by the rate of

hydrolysis

Nucleophilic subtituition

[1]

[1]

[1]

[1]

CH3 H

C = C

--- CH2 CH2----

CH CH2

S C = C

CH3 H

CH CH2

C = C

S

CH3 H

CH CH2

C = C

CH3 H

CH2 CH

C = C

CH3 H



42/42


(iv) Optical isomer

C3H7 C3H7| |

C CBr C2H5

CH3 C2H5 CH3 Br

[1]

[1]+[1]

TOTAL MARKS 15

[edu.joshuatly.com] trial kelantan stpm 2012 chemistry [94662c28].pdf

Documents