Stpm Trial 2009 Che Q&a Terengganu

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Name : …………………………………………………

NRIC : …………………………

JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR TRIAL JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR STPM 2009 JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR JABATAN PELAJARAN JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR NEGERI TERENGGANU JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR CHEMISTRY JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR PAPER 1 JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR One hour and forty-five minutes JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR

962/1

Instructions to candidates :

DO NOT OPEN THIS BOOKLET UNTIL YOU ARE 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. Answer all questions.Marks will not be deducted for wrong answers.The total score for this paper is the number of correctly answered questions.

This question paper consists of 14 printed pages.

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STPM 962/1 OTI 2 2009

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Section A

Four suggested answers labelled A, B, C and D are given for each question. Choose one correct answer.

1

The mass spectrum of iron shows peaks at mass number of 54, 56, 57, and 58. This shows that A B C D

2

The atoms of iron have different numbers of neutron The sample of iron is radioactive The sample of iron is not pure The atoms of iron have different numbers of proton

Which of the following gases is most likely to exhibit ideal behavior? A B

NH3 C4H10

C D

CO2 H2

P/atm

217

5.1

-57

3

T/OC

The phase diagram for carbon dioxide is shown above. Which of the following statements is not true? A B C D

4

374

The melting point of carbon dioxide increases with an increase in pressure. Solid carbon dioxide is denser than liquid carbon dioxide. Solid, liquid and gaseous carbon dioxide cannot exist in equilibrium at 1.0 atm. Carbon dioxide can be solidified at 1.0 atm by greatly reducing the temperature.

The electronic configuration of the outermost shell of an element is 3s2 3p1. What is the proton number for this element? A

3

B

11

C

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D

15

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STPM 962/1 OTI 2 2009 5

Which of the following has the biggest radius? A

6

SULIT*(CONFIDENTIAL*)

F–

B

Cl–

C

Na+

C D

Magnesium Phosphorus

D

Al3+

The information below describes an element, T. • • •

Melting point is 44OC Produces acidic oxides Monatomic in solid

Element T could be A B

7

Fluorine Sodium

The graph shows a property when going across period three. What could the property be? Property

Proton number

A B C D

8

Atomic size Ionization energy Electric conductivity Boiling point

Which of the following molecules will not form a hydrogen bond with another similar molecule? A B C D

C6H5OH CH3NH2 CH3CHO NH3

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STPM 962/1 OTI 2 2009

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9 Valence band

Conductor band

The diagram shows the conductor and the valence bands. Which of the following elements can be represented by the diagram shown? A B

10

C D

Neon Oxygen

The shape of a molecule depends on the following factors, except A B C D

11

Carbon Magnesium

The number of lone-pair electrons The number of bond-pair electrons The number of attractions between the electron orbitals The number of atoms bonded to the central atom

A chemist sketched a graph as shown below. Rate of reaction

Reactant

Products Time

Which of the following reactions can be represented byb the graph above? A B

12

Esterification Nitration

C D

Sulphonation Neutralization

Which of the following is true about the half life of a first order reaction? A B C D

The half life is longer for a catalyzed reaction. The half life is shorter when pressure increase. After the fourth half life, the percentage of the remaining element is 6.25% of the original quantity. The half life is influenced by the concentration of the reactant.

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STPM 962/1 OTI 2 2009 13

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The dissociation of dinitrogen tetroxide into nitrogen dioxide is represented by the equation below.

N2O4 (g)

2NO2 (g)

Ho = + 57.2 kJmol-1

If the temperature of an equilibrium mixture of the gases is increased at constant pressure , the volume of the mixture will A B C D

14

Increase, but only because of a shift of equilibrium towards the right Increase, both because of a shift of equilibrium towards the right and also because of thermal expansion. Stay the same, because any thermal expansion could be exactly counteract any thermal expansion Decrease, because a shift of equilibrium towards the left would more than counteract any thermal expansion.

Public swimming pools are often chlorinated to kill bacteria. As an alternative to chlorination silver ions can be used in a concentration of not more than 10-6 moldm-3 and not less than 10-7 moldm-3 of silver ions. Which of the following compounds would, in saturated solution, provided the necessary concentration of silver ion?

A B C D

15

solubility product

AgBr AgCl AgIO3 Ag2SO4

5 x 10-13 mol2dm-6 2 x 10-10 mol2dm-6 2 x 10-8 mol2dm-6 2 x 10-5 mol3dm-9

Distillation of a mixture of bromobenzene (C6H5Br) and steam at a pressure of 101kPa and a temperature of 95oC gave a distillate containing 100g water. The vapour pressure of water at 95oC is 85 kPa. What is the percentage by mass of bromobenzene in the distillate? (RMM C6H5Br = 156.5 ; H2O = 18.0) A B C D

16

compound

50% 62% 76% 100%

Some data relating to magnesium and its compounds are as follows? standard electrode potential of magnesium = -2.38V melting point of magnesium oxide = 2850o C melting point of magnesium chloride = 714o C What is the most suitable method for extracting magnesium metal from its ores? A B C D

Electrolysis of aqueous magnesium chloride Electrolysis of molten magnesium chloride Electrolysis of molten magnesium oxide Reduction of magnesium oxide with carbon

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STPM 962/1 OTI 2 2009 17

A current of 8A is passed through molten aluminium oxide using inert electrodes. What will be the approximate volume of gas liberated, measured at s.t.p ? A B C D

18

2.8 dm3 5.6 dm3 8.4 dm3 11.2 dm3

Which one of the following equation correctly defines the enthalpy change of formation of carbon monoxide? A B C D

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C(s) C(s) C(g) C(s)

+ ½ O2(g) + O (g) + ½ O2(g) + CO2(g)

CO(g) CO(g) CO(g) 2CO(g)

The enthalpy changes of formation of gaseous ethane and gaseous ethane are 52 kJmol-1 and 85 kJmol-1 respectively at 298K. What is the enthalpy change of reaction at 298K for the following process? C2H4(g) A B C D

20

+

H2(g)

C2H6(g)

-137 kJmol-1 -33 kJmol-1 +33 kJmol-1 137 kJmol-1

Four isomers of C6H12 are shown below.

CH

CH C

CH3 C

C

H

H

CH3

C2H5

CH3

C2H5

C2H5

H C

C

C CH3

CH3

C2H5

C

H

CH3

Which of the following pairs consists of a pair of cis-trans isomers? A B

1 and 2 1 and 3

C D

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STPM 962/1 OTI 2 2009 21

Neither exhibits cis-trans (geometrical) isomerism. Neither may be polymerized Neither reacts with bromine to give 1,4-dibromobutane Neither reacts with hydrogen to form butane.

Which one of the following reagents could best be used to distinguish between hex-1-ene and methylbenzene? Ag(NH3)2+ in H2O Br2 in CCl4 I2 in NaOH 2,4-dinitrophenylhydrazine in CH3OH

A B C D

23

24

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Which one of the following is a correct statement about the two alkenes CH3CH2CH=CH2 and CH3CH=CHCH3? A B C D

22

7

Compound G has the molecular formula C8H9C1. When compound G is heated with acidified potassium manganate(VII), a compound with the molecular formula C8H6O4 is formed. Compound G is most probably A

C

B

D

Complete the following reaction equation.

`Ethanoyl chloride

2-hydroxybenzoic acid

A

B

C D

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STPM 962/1 OTI 2 2009 25

8

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Aldehyde and ketone are produced through catalytic oxidation of alkenes. One example of the reaction scheme is shown below where ethanal is produced from the oxidation of ethene.

Based on the scheme above, the product formed from catalytic oxidation of but-2-ene is A B C D

26.

CH3CH2CHO CH3CH2CH2CHO CH3COCH2CH3 CH2COCH3

A reaction between compound P, CH3COCH2CO2CH2CH3 and phenyihydrazine is the first step in synthesizing Antipyrine, a type of medicine used to control fever. The reaction scheme is as follows.

What could Q be? A B

C D

27.

Why is ethanoic acid a stronger acid in liquid ammonia than in water? A B C D

28

Ammonia is a stronger base than water. The molecules of ethanoic acid form a hydrogen bond with water. Ethanoic acid dissolves better in liquid ammonia than water. Ethanoic acid has a higher enthalpy of hydration.

Ethanol is more soluble in water when compared to ethyl ethanoate. Why is this?

A B C D

Ethanol is a polar molecule whereas ethyl ethanoate is not polar. Ethanol is not polar whereas ethyl ethanoate is polar. Hydrogen bonds are formed between the ethanol and water molecules. Hydrogen bonds are formed between ethyl ethanoate molecules.

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STPM 962/1 OTI 2 2009 29

9

SULIT*(CONFIDENTIAL*)

Which of the following compounds produces a white precipitate with ammonia? A

C

B

D

30.

Reagent R is most probably A B C D

31

32

Ammonia nitrate Ethanamide Alcoholic ammonia Methylamine

In an experiment, diluted hydrochloric acid was added to 2-aminopropanoic acid until the pH of the solution is 2. What is the shape of 2-aminopropanoic acid molecule that exists at this pH? A

C

B

D

The scheme shows

A B C D

cationic polymerisation anionic polymerisation coordination polymerisation condensation polymerization

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STPM 962/1 OTI 2 2009 33

Which of the following forms an ionic hydride? A B C D

34

Sodium Silicon Sulphur Chlorine

Aqueous aluminium chlorine has a pH less than 7 because A B C D

35

SULIT*(CONFIDENTIAL*)

the charge density of the aluminium ion is high. the aluminium ion undergoes hydrolysis aluminium chloride undergoes partial dissociation in water. aluminium chloride is a covalent compound.

A tetrachloride of Group 14, XCl4 has the following properties. (i) (ii) (iii)

It is easily hydrolysed. Unstable to heat. Decomposes at room temperature according to the equation XCl4

→

XCl2

+ Cl2

X could be A B C D 36

Which of the following best explain the decreasing thermal stability of the chlorides and oxides in the oxidation state of +4 of the Group 14 elements (carbon to lead ) in the Periodic Table when descending the group? A B C D

37

The bond energy increases. The first and second ionization energy decreases. The standard electrode potential decreases. Presence of the inert pair effect of the s orbital electrons.

Which of the following is correct regarding dinitrogen tetroxide, N2O4? A B C D

38

germanium carbon silicon lead

It is polar. It has a ‘V’ shape It is produced from NO2. It contains one unpaired electron.

Which of the following is true with regards to the ammonia molecule? A B C D

It is non-polar molecule. It has a trigonal planar shape The H− N− H bond angle is 107o. It contains two lone pairs of electrons.

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STPM 962/1 OTI 2 2009 39

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The scheme below shows the reactions between potassium iodide with hot concentrated sulphuric acid, and with aqueous siver nitrate, as well as the solubility of the precipitate Y in concentrated aqueous ammonia. Conc. H2SO4

Vapour X

heat

KI(s)

AgNO3 (aq)

Precipitate Y

Conc. NH3

Product

Which of the following is correct with regards to the colour of vapour X, colour of the precipitate Y, and the solubility of Y, in concentrated ammonia?

40

Colour of X

Colour of Y

Solubility of Y, in conc. NH3

A

Brown

White

Soluble

B

Purple

Yellow

Soluble

C

Purple

White

Insoluble

D

Purple

Yellow

Insoluble

Which of the following statements helps to explain why nickel can act as a catalyst in the hydrogenation of ethene at 200 oC according to the equation : H2C = CH2 (g) + H2 (g) → A B C D

CH3CH3 (g)

Nickel can exhibits variable oxidation states. Nickel has d orbitals that can form temporary bonds. Nickel can form stable intermediate with the reactants. Nickel is neutral in the hydrogenation process of H2C = CH2 .

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STPM 962/1 OTI 2 2009

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Section B

For questions 41 through 50, 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.

41

B

C

D

1 only is correct.

1 and 2 only are correct.

2 and 3 only are correct.

1, 2 and 3 only are correct.

Which of the following depends on the number of solute particles in a given mass of solvent? 1 2 3

42

A

Elevation of boiling point of solvent Depression of freezing point of solvent Vapor pressure of solute

Hydroxyapatite, Ca5(PO4)3OH is the main constituent of tooth enamel . In the presence of saliva, the following equilibria exist. Ca5(PO4)3OH (s) HPO42- (aq)

5Ca2+ (aq) + 3PO43- (aq) + OH- aq) H+ (aq) + PO43- (aq)

Which of the following statements help to explain why tooth enamel is dissolved more readily when saliva is acidic? 1 2 3

43

The hydroxide ions are neutralised by the acid The phosphate ion PO42- (aq) accepts H+ (aq) Calcium ions react with acids

The dissociation constants, Ka, for three acids are given below:

Acid phenylethanoic acid 3-hydroxybenzoic acid 2-chlorobutanoic acid

Ka (moldm-3) 4.90 x 10-5 8.32 x 10-5 1.15 x 10-3

Which of the following statement is/are correct about the acid? 1 2 3

Ka for 2,2-dichlorobutanoic acid is greater than Ka for 2-chlorobutanoic acid [H+] in 1.00 moldm-3 phenylethanoic acid solution is 4.90 x 10-5 3-hydroxybenzoic acid is the strongest acid

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STPM 962/1 OTI 2 2009 44

Under which of the following conditions would the Partition Law not hold? 1 2 3

45

SULIT*(CONFIDENTIAL*)

When the solutions are concentrated When the solute dissociate or associate in the solvents When the temperature changes

Which pairs of compounds can react to produce a compound with the following structural formula?

1

2 3

46

Which of the following compounds can be used to prepare diazonium salt when reacted with nitric acid(III)?

1

2

3 47

Which of the following statements explain the increasing thermal stability of the carbonates of the Group 2 elements (beryllium to barium) when descending the group?

1 2 3

48

When the solutions are concentrated When the solute dissociate or associate in the solvents When the temperature changes

Which of the following aqueous cations would give a precipitate when excess ammonia is added to it? 1

Al3+

2

Zn2+

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Cu2+ [Lihat sebelah(Turn over SULIT*(CONFIDENTIAL*)

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49

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In the diaphragm cell for the manufacture of chlorine by elavtrolysis of brine. The function of the diaphragm

1 2 3

50

14

is to separate the anode compartment from the cathode compartment. is to prevent the reaction between chlorine and sodium hydroxide produced. Is to act as catalyst to speed up the electrolysis process.

A complex salt with the formula of [Ni(NH3)x(H2O)y]Cl2 has the composition by mass of nickel, 13.98%; and hydrogen, 3.79%. Which of the following statements are true with regards to the complex salt?

1 2 3

The ratio of x to y in the formula of the salt is 2:1. The name of the complex salt is diaquatetraamminenickel(II) chloride. The cis isimer of the complex is optically active.

END OF QUESTION PAPER

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CONFIDENTIAL* Name : ………………………………………………… NRIC : ………………………… JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR JABATAN962 PELAJARAN JABATANPELAJAR / 2 ERENGGANUJABATANPELAJARAN TERENGGANU OTI 2 JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR STPM 2009 JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR JABATAN PELAJARAN TERENGGANU JABATANPELAJAR JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN NEGERI TERENGGANU TERENGGANU JABATANPELAJAR JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN CHEMISTRY TERENGGANU JABATANPELAJAR JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR PAPER 2 JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR STRUCTURE AND ESSAY JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR JABATAN PENLAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA

Two and a half hours

Instructions to candidates :

Answer all the questions in Section A in the spaces provided. Answer any four questions from section B. For this section, write your answers on the answer sheets provided. Begin each answer on a fresh sheet of paper. Answers should be illustrated by large, clearly labeled diagrams wherever suitable. Answers may be written in either Malay or English. Arrange your answer in numerical order and tie the answer sheets to this booklet.

For examiner’s use Section Marks Marks Obtained 1 10 2 10 A 3 10 4 10 40 5 15 6 15 B 7 15 8 15 9 15 10 15 60 TOTAL 100

This question paper consists of 11 printed pages STPM 962/2 *This question paper is CONFIDENTIAL until the examination is over.

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CONFIDENTIAL *

Section A (40 Marks) Answer all questions in this section. 1

(a) The relative atomic mass of X is 79.99. (i) Why is the relative atomic mass of X not a whole number? …………………………………………………………………………………….. [1 mark] (ii) In nature, X contains two isotopes with mass numbers 79 and 81. Calculate the percentage abundance of the isotopes 79X and 81X.

(iii) If X exist as a monoatomic element,sketch the mass spectrum of X.

[2 marks]

[2 marks] (b)

Graph

against p for 1.0 mol H2 and CO2 at 273K is shown below:

H2 CO2

Ideal gas

(i)

Explain why carbon dioxide behaves like an ideal gas at low pressure. ………………………………………………………………………………… ………………………………………………………………………………… [1 mark]

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[Turn over CONFIDENTIAL*

(ii)

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What type of deviation from ideal gas behaviour for hydrogen. ……………………………………………………………………………. [1 mark]

(iii)

Why hydrogen shows only deviation in (ii). ………………………………………………………………………………. [2 marks]

2

(a)

The following diagram shows an arrangement of an electrochemical cell created from two half- cells, A and B.

(i)

Write the overall equation for the above cell

[1 mark] (ii)

With reference to the Data Booklet, calculate the electromotive force(e.m.f) of the under standard condition.

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(iii)

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CONFIDENTIAL *

Using the result obtained in(ii),write the Nernst equation of the above cell reaction.

[1 mark] (b)

(i)

On the incomplete outline below sketch the Born-Haber cycle which includes the standard enthalpy change of formation, /\H, and the lattice energy of calcium sulphide. Label all the enthalpy changes involved and the chemical species at each stage. [Abbreviations can be used, as in part (b).]

Ca2+(g)

+

S2-(g)

Energy

Ca(s)

+

S(s)

CaS(s)

[5 marks]

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(ii)

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CONFIDENTIAL *

The standard enthalpy changes of atomisation, ∆H0a of calcium = 178 kJ mol-1 ∆H0a of sulphur = 279 kJ mol-1 The sum of the first two electron affinities of sulphur = 337 kJ mol-1 The standard enthalpy change of formation, ∆H0a of calcium sulphide = - 487 kJ mol-1. First ionisation of Calcium = +590 kJmol-1 Second ionisation of Calcium = +1150 kJmol-1 Calculate the lattice energy of calcium sulphide.

[2 marks] 3

(a)

Write the equations for the reaction of ethanoyl chloride, CH3COCl, with 1-propanol, CH3CH2CH2OH, and aniline, C6H5NH2. Name the organic products formed. (i)

1-propanol

(ii)

Aniline

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(b)

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CONFIDENTIAL *

Write an equation to show how aniline can be obtained from the product formed in (a)(ii) above.

[1 mark] (c)

Give the formulae of the products obtained when the following ester O O ║ ║ OCH2CHOCCH2CH2C

│

CH2 is heated with aqueous sodium hydroxide.

[2 marks] (d)

(i)

Give the structural formulae of the reagents that are required to produce COOH Compound X,

(ii)

O-C-CH3 , by a one step reaction. ║ O

State a use for compound X.

[3 marks] 4

(a)

When ammonium nitrate is heated,it liberates a colourless gas. The gas can be used as an anaesthetic. (i)

Give the name of the gas

(ii)

………………………………………………………………….…………… [1 mark] Write the equation for the above reaction. …………………………………………………………………………….… [1 mark]

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7

CONFIDENTIAL *

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On the axes below,sketch the general trend for each property of the elements or their compound the third period of the Periodic Table. No scale is given for the vertical axis.Your sketch is expected to be clear but only qualitative. Expalain the changes shown. Melting point of oxides (oC)

Na Mg Al Si

PS

[1 mark]

Explanation ………………………………………………………………………………………. ..................................................................................................................................... ……………………………………………………………………………………….. [3 marks] (b)

Chromium (proton number = 24) is a d-block element. A lot of chromium compound are used in the laboratory. (i)

Write the electronic configuration for the Cr3+ ion. ………………………………………………………………………..……….. [1 mark]

(ii)

Briefly explain why the Cr3+ (aq) ion is coloured. ………………………………………………………………………………. ………………………………………………………………………………. ……………………………………………………………………………… [3 marks] .

STPM 962/2 *This question paper is CONFIDENTIAL until the examination is over.

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5

(a)

State the difference between the hydrogen emission spectrum and a spectrum produced by a tungsten filament bulb. [2 marks]

(b)

States all the orbitals for the carbon atom and state the differences between them. [2 marks]

(c)

Hund`s rule, Pauli exclusion principle and Aufbau principle are used to determine the ground states electronic configuration of an atom.

(d)

6

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8

CONFIDENTIAL *

(a) (b)

(c)

(d)

(i)

State the rule and principles.

(ii)

Describe how the two principles are applied to oxide ion O2-, as an example. [3 marks]

(i)

What is meant by the atomic radius of an element?

(ii)

State and explain the changes in the radius of the atom of elements in Period 2, that is, from lithium to neon. [4 marks]

[3 marks]

[ 1 mark]

Predict the shape of the NH3 molecules and NH4+ ions , explain the differences in their bond angel. [4 marks] Draw a labeled diagram showing the overlapping of orbitals in (i) H2O [2 marks] (ii) C2H4 [2 marks] The boiling point of H2O is higher than HF.Explain. [2 marks]

The rate of decomposition of acidic hydrogen peroxide can be analysed through titration. Hydrogen peroxide samples with a fixed volume are taken at specific times and were titrated with potassium manganate(IV) solution. The titration results are as follows: Time/min Volume of KMnO4(aq)/cm3 (i) (ii)

0

10

20

30

45.5

27.4

16.4

9.9

Determine the half-life of this reaction by plotting the graph, using the data from the table above. [4 marks] What is the order of this reaction? [1 mark]

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7

(a)

State Le Chatelier’s principle.

Referring to the equilibrium 4NO(g) 4NH3(g) + 5O2(g) (b)

(c)

+

[2 marks]

6H2O(g)

(e)

(i)

the effect on the yield of NO when pressure on equilibrium mixture is increased

(ii)

the effect on equilibrium constant, Kc when temperature on the equilibrium mixture is decreased. [4 marks]

If 0.40 mol of NH3 and 0.50 mol of O2 in a 1 dm3 container is allowed to react in the presence of catalyst Platinum/Rhodium until an equilibrium is established, the yield of NO is 30% by mole. Calculate the number of mol of NO produced. [2 marks] B

is second order.

Sketch the graphs of (i) concentration of A versus time and (ii) rate versus concentration of A.

If the graph of

[2 marks]

1 versus time is as given below. [A]

Calculate (i) the rate constant (ii)

∆H = –908 kJ mol–1

Explain

Given that the reaction A (d)

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9

CONFIDENTIAL *

the initial concentration of A

1 / mol–1 dm–3 [A]

12.

2.0 20

0

(f)

Suggest the mechanism for the reaction

A

STPM 962/2 *This question paper is CONFIDENTIAL until the examination is over.

B

t / min

[3 marks]

[2 marks]

[Turn over CONFIDENTIAL*

8

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10

CONFIDENTIAL *

(a)

Describe and explain the variation in boiling point of the tetrachlorides of Group 14 from Carbon to lead [4 marks]

(b)

How and why do CCl4 and SiCl4 differ in their reaction with water? Include,in your answer any reaction that occurs. [4 marks]

(c)

Suggest a use of each element or compound below, and explain how each of the uses is related to physical or chemical properties and structure. (i) Silicon (ii) Silicon (IV) oxide (iii) Carbon dioxide

9

[3 marks]

(d)

Aluminium is extracted from a mixture of molten aluminium oxide and cryolite, Na3AlF6 by electrolysis. Suggest factors that have to be taken into consideration when choosing a site for an aluminium factory. State one adverse effect on the environment as a result of the extraction process of aluminium. [4 marks]

(a)

An alkene, C4H8 reacts with hydrogen chloride to produce a compound, C4H9Cl, draw the structure of the alkene and the chloro-compound. [2 marks]

(b)

With reference to the reaction scheme below.: Cl2/ light

A

C2H6

NaOH reflux

B

Step 1

Conc. H2SO4

180oC

C

Br2/CCl4

D

(i)

Identify compounds A to E.

(ii)

Name the reagent used in step I.

(iii)

Give an important use for compound E.

STPM 962/2 *This question paper is CONFIDENTIAL until the examination is over.

NaOH Reflux

E

[7 marks] [Turn over CONFIDENTIAL*

(c)

10

(a)

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11

CONFIDENTIAL *

Suggest how you would differentiate the following pairs of compounds by chemical means. (i)

1-iodohexane and 1-chlorohexane

(ii)

chlorocyclohexane and chlorohexane

(iii)

1-chloro-1- butane and 1- chlorobutane

[6 marks]

The structural formulae of two amines are shown below.

Tetrahyroquinoline Tetrahydroisoquinoline Which is the stronger base? Explain (b)

[2 marks] Suggest ,with reasons.how the basicity of 3,4-difluorophenylamine might campare with that of phenylamine.

3,4-Difluorophenylamine

(c)

[2 marks] Ziegler-Natta catalyst is a mixture of titanium(IV) chloride, TiCl4 and triethylaluminium, Al(CH3CH2)3, Explain the addition polymerisation mechanism with the ziegler-Natta catalyst to produce poly(ethene). [6 marks]

(d)

Give two advantages of addition polymerisation with the Ziegler-Natta catalyst campared to addition with free radical polymerisation in the production of poly(ethene) [3 marks]

(e)

Nylon has similar characteristics with a few natural compounds.What are these compound? Explain. [2 marks] END OF QUESTION PAPER

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Name : …………………………………………………

NRIC : …………………………

JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA TRIAL JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU STPMJABATANPELAJA 2009 JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA JABATAN PELAJARAN JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA NEGERI TERENGGANU JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA TRIAL EXAMINATION 2009 JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA CHEMISTRY JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA PAPER 1 & 2 JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA

962/1

MARKING SCHEME

This answer paper consists of 17 printed pages

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2

OTI 2 2009

STPM

STPM CHEMISTRY 962/1 OTI 2 2009 MARKING SCHEME PAPER 1 Question No.

Answer

1

A

2

D

3

D

4

C

5

C

6

D

7

C

8

C

9

B

10

C

11

A

12

C

13 B

14 A

Explanation These are the isotopes of iron. Different isotopes have different numbers of neutron Of the 4 gasses given hydrogen gas is most likely to exhibit ideal behavior. Refer to any graph of (pV/nRT) against p. Carbon dioxide cannot be solidified at 1.0 atm if the temperature is greatly reduced. At 1.0 atm CO2 exists in both solid and gaseous forms. Actual electronic arrangement is 1s2 2s2 2p6 3s2 3p1. Total number of electron is 13. Thus the proton number is 13 Na+ is the biggest as it has the smallest number of nuclear charge. The smaller the nuclear charge, the bigger the ionic size. Only phosphorus can exist as monatomic solid with acidic properties in its oxides. Across period 3 from left to right, conductivity increases for the first 3 elements, then starts to decrease as the elements become metalloid, and decreases further as elements are non-metals. In the CH3CHO molecule, hydrogen atom is bonded to carbon not oxygen. So no intermolecular hydrogen bonds. No energy gap between the two bands, so it belongs to a metal, which is magnesium. There are only repulsive forces exist between electron orbitals. So the lone pair electrons push each other so that the angle between them is maximized. The graph is reversible reaction. The rate of the forward reaction is equal to the rate of the backward reaction over time. The formation of ester is a reversible reaction. e.g.: if the original sample = 100g 100g → 50g → 25g → 12.5g → 6.25g t1/2 t1/2 t1/2 t1/2 Percentage remaining after the 4th half life = 6.25 x 100 = 6.25% 100 Since the forward reaction is endothermic, an increase in temperature shifts the equilibrium to the right according to Le Chatelier’s principle, by absorbing the excess heat. In the case, more gas particles are produced and there is an increase in volume. Furthermore, heating will also cause the gases to expand. AgBr (s)

Ag + (aq) + Br-(aq)

Ksp = [ Ag+ ] [Br- ] = 5 x 10 -13 mol2dm-3 But [ Ag+ ] = [Br -] [ Ag+ ] = ( 5 x 10 -13 )1/2 = 7.1 x 10-7 moldm-3

Marking scheme OTI 22009

Question No.

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3

OTI 2 2009

STPM

Answer

15 B

Explanation mB = MB x PoB mW MW x PoW mB = 156.6 x (101 x 85) 100 18 x 85 = 163.66 % bromobenzene =

163.66 (1663.66 + 100)

x 100

= 62% 16 B

The very negative Eo value of Mg shows that Mg2+ is very difficult to be reduced to Mg. Therefore, normal chemical reduction is not suitable. A feasible way would be the electrolysis of molten Mg2+ , in this case, MgCl2 (MgCl2 has a lower m.p. than MgO).

17 A

2O2-(l)

O2(g) + 4e

Quantity of electricity used = I x t = 8 x (100 x 60) = 48000 C Amount of electrons passed = 48000C 96000 Cmol-1 = 0.5 mol Amount of O2 evolved = 0.5 4 = 0.125 mol Volume of O2 evolved = 0.125 x 22.4 = 2.8 dm3 18 A

The enthalpy change of formation of CO is the enthalpy change when 1 mol of gaseous CO is formed from its constituent elements, that is C and O2, at their standard states.

19

H = -52 + (-85) = - 137 kJmol-1

A 20 A

For cis-trans isomers, 2 different groups must be bonded to the same C at the double bond. B : 1 and 3 are identical C : 1 and 4 are structural isomers D : 2 and 4 are structural isomers

Marking scheme OTI 22009

Question No.

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OTI 2 2009 Answer

STPM Explanation

21 C 22 B

Upon reacting with Br2 , but-1- ene gives 1,2- dibromobutane and but -2-ene gives 2,3- dibromobutane. Being an alkene, hex-1-ene undergoes electrophilic addition readily with Br2 in CCl4 and decolourised it. Methylbenzene is unable to do so. CH3(CH2)3CH=CH2 + Br2

23

A

24

A

25

B

26

A

CH3(CH3)3CHBr—CH2Br

Remember: Ethanoyl chloride (acyl chloride) will react with alcohols but not with carboxylic acids. CH3CH2COOH All carbonyl compounds, which are aldehyde and ketone react with 2,4-dinitrophenyihy- drazine to form orange precipitate that has a high melting point. Ethanoic acid is a weak acid and it partially ionises in water to produce hydroxonium ion, H+. CH3COOH + H20 CH3COO- + H If ethanoic acid is dissolved in a base like ammonia that is able to extract the proton (H+) from ethanoic acid more effectively, more ethanoic acid molecules will ionise. Thus H+ ions are produced are the strength of ethanoic acid will increase. Thus ethanoic is a stronger acid in liquid ammonia than in water.

27

D

The reaction equation is as follows. Remember: This molecule contains phenyihydrazine carbonyl group.

28

C

Hydrogen bonds are formed between ethanol and water molecules. Thus ethanol is soluble in water.

Whereas ethyl ethanoate (ester) that has a long carbon chain does not form hydrogen bonds with water, thus it is less soluble in water

Marking scheme OTI 22009

Question No.

Answer

29

C

30

D

31 D

32

B

33

A

34

A

35

D

D

STPM Explanation

chloride An aromatic amine with an amino group at its side chain will have similar chemical properties as an aliphatic amine.

At pH 2, an acidic solution and 2-amino- propanoic acid (alanine)will exist as positive ions.

The reaction results in a nucleophilic addition to the double bond and the anionic polymerisation process takes place.

NaH – ion, SiH4 - covalent, H2S – covalent, HCl – covalent. The sodium atom wiyh the biggest size among the four elements has the lowest ionization energy and can lose electron readily to form ionic compound. Aluminium is a amphoteric. It si soluble in aqueous sodium hydroxide. Al2O3 (p) + 2OH- (aq) + 3H2O(l) → 2[(OH)4]- (aq) XCl4 decomposes at room temperature showing that the X-Cl bond is very weak. Hence, X must have the biggest size in Group 14. PbCl4(l)→

36

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5

OTI 2 2009

PbCl2 (s)

+ Cl2 (g)

The inert pair effect increases going down the Group 14. Hence, the +2 state becomes progressively more stable while the + 4 state becomes less stable.

Marking scheme OTI 22009

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6

OTI 2 2009 Question No.

Answer

37

C

STPM Explanation

The Lewis structure of N2O4 is as follows :

It is a symmetrical molecule. Hence is non-polar. There are 3 bond pairs with no lone pairs surrounding the nitrogen atom. Hence, its shape is triginal planar and not ‘V’ shape. As can be seen from the Lewis diagram all the electrons in N2O4 are paired. N2O4 is formed from the dimerisation of NO2. 2NO2 N2O4 38

C

39

D

The lone pair electrons in NH3 pushes the three bonding pairs closer to one another. Hence, its bond angle is slightly less than that of a perfect tetrahedron, 109.5o .

KI reacts with H2SO4 to produce iodine, which is a purple fume. KI + H 2SO4 → KHSO4 + HI(g) 2HI(g) + H2SO4 → I2(g) + SO2(g) + 2H2O

KI reacts with silver nitrate to produce silver iodide, which is yellow. KI(aq) + AgNO3 (aq) → KNO3 (aq) + AgI(s)

40

B

41

B

42 B(1,2)

43 A( 1 ) 44 D(1,2,3)

45

D

AgI is insoluble in either dilute or concentrated ammonia. Heterogeneous catalyst uses their empty d orbitals to form temporary bonds with the reacting molecules. This process is known as adsorption. 1 Elevation of boiling point of solvent 2 Depression of freezing point of solvent According to Le Chatliers Principle, When OH- ions are neutralized by the acid, position of eq will shift to the right, making the solid Ca5(PO4)3OH dissolved. When the PO43- ions accepts H+ , the eq will shift to the right, making the solid Ca5(PO4)3OH dissolved.

Halogen is an donating group which decreases the acid strength.( Ka is greater) Partition law can only be used under the following condition - the solutions must be dilute - the solute cannot undergo dissociation or association in one solvent and not the other - the temperature must be fixed The Grignard reagent has the general formula, RMgX. With ketones, a

Marking scheme OTI 22009

Question No.

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OTI 2 2009 Answer

STPM Explanation

tertiary alcohol is produced. Remember: The C—Mg and C—Li bonds are very polar. When either the C—Mg or the C—Cl bonds undergoes fission, the carbon acts as a nucleophile 46

A

47

A

48

C

49

B

50

B

To form a diazonium salt, nitric(III) acid must react with a primary aromatic amine solution at a temperature of 0 — 5°C. 2-methylphenylamine, is a primary aromatic amine. Going down group 2, the size of the cation increases causing the polarizing power to decrease. Statement 2 only indicates that the oxides are more stable than the carbonates. It does not explain about the stability trend of the carbonates. Zn(OH)2 and Cu(OH)2 are soluble in excess ammonia. Mol ratio of Ni : N : H = 13.98/59 : 13.27/14 : 2.79/1 = 0.236 : 0.947 : 3.79 = 1 : 4 : 16 :. Ratio of H2 : N = 8 : 4 = 2 : 1 The complex does not contain polydentate ligands. Hence, it cannot exhibits optical isomerism.

Marking scheme OTI 22009

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8 STPM CHEMISTRY OTI 2 2009/TRIAL

EXAM

MARKING SCHEME PAPER 2 SECTION A ( Structured Question ) QUESTION SUGGESTED ANSWERS NO The element X contains isotopes. 1(a)(i) 1(a)(ii)

Lets the percentage abundance of Percentage abundance of

SUGGESTED MARKS 1

79

X = x%

1 or 1

81

X = (100-x)%

1

79.99 = X = 50.5

1

Percentage abundance of isotopes 79X = 50.5% Percentage abundance of isotopes 81X = 49.5%

Any 2

1(a)(iii) Abundance(%) Axis labeled and unit 1

50.5 49.5

Draw a correct peak 1 79

80

81

m/e

1(b)(i)

1(b)(ii)

At low pressure, the molecules are far apart , so repulsive forces among the molecules of CO2

1 1

Positive deviation

1

Forces of repulsion between the H2 gas molecules which causes the speed of H2 molecule collision with the vessel wall to increase. So the pressure of H2 is higher, causing > 1 (positive deviation)

1 1

Total

10

1(b)(iii)

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9 QUESTION SUGGESTED ANSWERS NO Zn(s) + 2Ag + (aq) → Zn 2+(aq) + 2Ag(s) 2 (a) (i) 2 (a) (ii)

2 (a) (iii)

Half cell reaction Zn2+(aq) + 2e→ Zn(s) 2Ag+ (aq) + 2e → 2Ag(s) Zn(s) + 2Ag+ (aq) → Zn2+(aq) + 2Ag(s) E.m.f. of cell = 0.80 + 0.76 = 1.56 V

SUGGESTED MARKS 1 E0/V -0.76 +0.8

1 1 1

Ecell — Eceii° - 0.059 log [Zn2+] 2 [Ag]2

1

5 For every single level energy shown,one mark will be given

2 (b) (i)

Latice energy CaS(s)

2 (b) (ii)

-487 = 178 + 279 + (590 + 1150) + 337 + Lattice energy Lattice energy = -3021 kJ mol-1 Total

3 (a) (i)

CH3COCl + CH3CH2CH2OH → CH3COO CH2CH2CH3 + HCl Propyl ethanoate

3 (a) (ii)

CH3COCl

3 (b)

+ C6H5NH2 →

Heat with dilute sulphuric acid. CH3CONH C6H5 + H2O →

CH3CONH C6H5 + HCl N-phenyl ethanamide

1 1 1 1 1

CH3COOH + C6H5NH2

3 (d) (i)

Structural formulae of the products : HOCH2CHOH and NaOOCCH2COONa │ CH3 Heat 2-hydroxybenzoic acid with ethanoyl chloride.

3 (d) (ii)

X is aspirin. It is an analgesic.

3 (c)

1+1 10

1+1 1 1 1 Total

10

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10 QUESTION NO 4 (a) (i)

Dinitrogen oxide, N2O

4 (a) (ii)

NH4NO3(s) → N2O(g)

4 (b)

SUGGESTED ANSWERS

+

SUGGESTED MARKS 1

2H2O(l)

1

Melting point of oxides

1

Na Mg Al Si P S Explanation: Na2O and MgO, ionic with strong electrostatic forces;Al2O3, ionic with Covalent character; SiO2 macromolecular with high melting point; Oxides of P and S,simples molecules

1 1 1

4 (c) (i)

4 (c) (ii)

1

3d electrons absorb energy in the visible wavelengths except the green wavelength which it reflects and jump to the higher set of vacant 3d orbitals. Therefore, Cr3+ ions appear green.

1+1

1

Total

10

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11 QUESTION SUGGESTED ANSWERS NO The hydrogen emission spectrum consist of discrete lines 5(a) whereas the spectrum produced by the tungsten filament bulb is a continuos spectrum. 1s,2s,2px,2py 5(b) The difference between 1s and 2s is that the size of 2s is bigger than 1s. or The difference between 2s and 2p is that 2s is spherical but that 2p is dumb-bell shape.

5(c) (i)

Hund`s rule: When electrons are placed in a set of orbital with equal energies, the electrons must occupy them singly with parallel spin before they can occupy the orbital in pairs. Pauli exclusion principle: Each orbital can only be filled with two electrons with opposite spins. Aubau principle: Electrons occupy orbitals in order of the energy levels of the orbitals. Orbitals with the lowest energy are always occupied first.

5(c) (ii)

SUGGESTED MARKS 1 1 1 1 or 1 ………… Max 2 ………... 1

1

1

Number of electrons in O2- ion = 8+2=10 Step 1: Apply Pauli exclusion principle and Aufbau principle.Fill 1s orbital with two electrons.

1 1s 2s 2p Step 2:Fill 2s orbital with two electrons 1

1s 2s 2p Step 3: Apply Hund`s rule. Fill 2px,and 2py orbitals wih three electrons. The electrons must be in parallel spins.

1s 2s 2p Step 4: Fill the remaining three electrons in 2px,2py and 2pz orbitals . Each pair of electrons must be in parallel spins.

1s

2s

2p

1

1 Describe or show the filling using a diagram Any 3

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12 QUESTION SUGGESTED ANSWERS NO Atomic radius is defined as half the distance between the nuclei of two 5(d) (i) closest and identical atoms. 5(d) (ii)

When across a period(from lithium to neon), atomic radius decreases. Because the nuclear charge increases(number of protons) But the screening effect remains almost constant as the number of shells remain the same. The attraction of the valence electrons by the nucleus increases. Total

6 (a)

NH3 Valence electron, N : 5e 3H : 3e ------------8e -------------

3 bond pair, 1 lone pair

.. N Or 107

H

trigonal pyramidal

0

H

H

NH4+ Valence electron, N : 5e 4H : 4e Positive charge : -1e (less 1 electron) ------------8e --------------

4 bond pair, no lone pair

SUGGESTED MARKS 1

1 1 1 1

15

1

Draw or state the shape 1

1

+ H

N

Or

tetrahedral

109.5)

H

H

H

The bond angle of NH3 is 1070 wheares the bond angle of NH4+

Draw or state the shape 1

Any 4

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13 QUESTION NO H2O 6 (b) (i)

SUGGESTED ANSWERS

SUGGESTED MARKS

H(1 s)

Overlapping 1 sp3 orbitals

label 1

O H(1 s)

..

6 (b) (ii) C2H4

π

H(1s)

H(1s)

δ

Overlapping 1

H(1s)

H(1s) C

6 (c)

6 (d) (i)

C

Boiling point of H2O is higher than HF because each HF molecule forms 2 intermolecular hydrogen bonds compared to 4 intermolecular hydrogen bonds formed by each H2O molecule. Volume of KMnO4

label 1

1 1

Label the axis and unit 1

40 Plot the graph 1+1 30 Indicate on the graph t1/2

20

1 10 t1/2= 13.5

10

t1/2= 13.5

20

30

t/min

From the graph, the half- life of the reaction is 13.5 minutes.

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14 QUESTION SUGGESTED ANSWERS NO From the graph, half life doesnot depend on the concentration of 6 (d) (ii) hydrogen peroxide. Thus, the reaction is first order. 7(a)

SUGGESTED MARKS

1

Total When an equilibrium is disturbed then equilibrium will shift in the direction that will reduce the effect of the disturbance.

15 2m

7(b)(i)

Yield of NO decreases. When pressure is increased, equilibrium will shift to the left because the backward reaction will reduce the number of gaseous molecules.

1m 1m

7(b)(ii)

Value of Kc increases. The forward reaction is exothermic, the Kc value decreases with increase in temperature.

1m 1m

7(c)

Let x be the number of mol of NO produced Total number of moles at equilibrium = 0.40 – x + 0.50 – 1.25x + x + 1.5x or x = 30 % 0.4 x + 0.5 1.25x + x + 1.5x

1m

1m

x =0.29 mol

7(d)

(ii)

(ii) [A]

Rat

t

0 7(e)(i)

0

[A

1 1 = kt + [A] [A]0

k= 7(e)(ii)

]

1m

12.0 − 2.0 = 0.40 mol–1 dm3 min–1 25

1 [A]0

1m

= 2.0 1m

[A]0 = 0.50 mol dm–3

7(f)

A + A → M M → 2B

1m 1m

slow step fast step

Total

15

papercollection

15 QUESTION SUGGESTED ANSWERS NO Boiling point of tetrachlorides increases down the group 8 (a)

8 (b)

SUGGESTED MARKS 1

All the tetrachlorides are non-polar and are simple molecules.

1

Molecular size increases from top to bottom.

1

Strength of van der Waals forces increases down the group.

1

SiC14 undergoes hydrolysis whereas CCI4 does not. This is because the Si atom has empty d orbitals which can be attacked by lone pair electrons from water molecules. The product of hydrolysis is silicon(IV) oxide and hydrochloric acid.

1 1

1 1

, C atom in tetrachioromethane does not contain empty d orbitals, hence does not undergo hydrolysis. 8 (c) (i)

Semiconductor

1

Semimetal, electrical conductivity increases when temperature is raised. Ceramic The Si—O covalent bond in the giant covalent network is strong. In fire extinguishers. Does not support combustion 8 (d)

1 1

An aluminium factory has to be located near a port so that the raw material, bauxite ore, can be easily transported to it. This will reduce cost.

1

1 As the electrolysis of molten aluminium oxide involves the use of a large amount of electricity, the aluminium factory must be located close to a hydroelectric dam for a supply of cheap electricity. These two factors can help to reduce the cost of producing aluminium. One bad effect on the environment caused by the extraction of aluminium is the release of poisonous hydrogen fluoride and fluorine gas into the air, which are formed during electrolysis of a mixture of aluminium oxide and cryolite.

Total

1 1

15

papercollection

16 QUESTION NO 9(a)

SUGGESTED ANSWERS

SUGGESTED MARKS

CH3-CH=CH-CH3 CH3- CH- CH2-CH3 2m Cl

9(b)

A: CH3CH2Cl B : CH3CH2OH C : CH2=CH2

D : CH2Br- CH2Br E : CH2OH – CH2OH 5m

9(c)

Ethanolic KOH

1m

9(d)

monomer for polyester

1m

9 (e)

- heat with ethanolic silver nitrate 1-iodohexane : yellow precipitate of AgI 1- chlorohexane : white precipitate of AgCl - heat with ethanolic silver nitrate Chlorocyclohexane : white precipitate Chlorobenzene : no precipitate - add acidified KMnO4 1- chloro-1- butane : decolourisation of KMnO4 1- chlorobutane : KMnO4 solution is not decolourised.

1+1

1+ 1

1+ 1 Total

15

papercollection

17 QUESTION SUGGESTED ANSWERS NO Tetrahydroisoquinoline is the stronger base. In tetrahydroquinoline, the 10 (a) unshared electron pair is delocalised into the aromatic ring, making it less available to accept a proton, whereas tetrahydroisoquinoline resembles an alkylamine.

SUGGESTED MARKS 1 1

10 (b)

3,4-Difluorophenylamine is a weaker base than phenylamine because the two F atoms are electron-withdrawing and they reduce the availability of the lone pair of electrons on the N atom to accept a proton.

1 1

10 (c)

An ethyl group, CH3CH2 is transferred from triethylaluminium to titanium(IV) chloride to produce a complex,

1

1

Ethene molecules act as Lewis bases and are bonded to titanium which has vacant d orbitals. These ethene monomers are inserted between the titanium and the ethyl group to form a polymer.

1 1

1

The process is terminated when a hydrogen atom is added to a titanium atom, and the poly(ethene) chain is separated from titanium. 10 (d)

The poly(ethene) polymer formed by the addition polymerisation process using the Ziegler-Natta catalyst is a linear polymer and of high density and high melting point.

10 (e)

Proteins and polypeptides.

1

1 1+1

1 1

Nylon has peptide linkages, CONH, which are also found in proteins and polypeptides. Total

15