stpm trial 2009 che q&a terengganu

8/14/2019 STPM Trial 2009 Che Q&A Terengganu

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Name : NRIC :

JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR



JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJARJABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR











JABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJARJABATAN PELAJARANTERENGGANUJABATANPELAJARAN TERENGGANUJABATANPELAJAR









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.

Answerall 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.

TRIAL

STPM 2009

CHEMISTRYPAPER 1

One hour and forty-five minutes

962/1

JABATAN PELAJARAN

NEGERI TERENGGANU

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STPM 962/1 OTI 2 2009 SULIT*(CONFIDENTIAL*)

STPM 962/1 OTI 2 2009 [Lihat sebelah(Turn over

Kertas soalan ini SULIT sehingga peperiksaan ini tamat SULIT*(CONFIDENTIAL*)

2

Section A

Four suggested answers labelledA, B, CandDare 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 The atoms of iron have different numbers of neutron

B The sample of iron is radioactive

C The sample of iron is not pure

D The atoms of iron have different numbers of proton

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

A NH3 C CO2

B C4H10 D H2

3 The phase diagram for carbon dioxide is shown above. Which of the following statements is

not true?

A The melting point of carbon dioxide increases with an increase in pressure.

B Solid carbon dioxide is denser than liquid carbon dioxide.

C Solid, liquid and gaseous carbon dioxide cannot exist in equilibrium at 1.0 atm.

D Carbon dioxide can be solidified at 1.0 atm by greatly reducing the temperature.

4 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 13 D 15

P/atm

-57 374 T/OC

217

5.1

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3

5 Which of the following has the biggest radius?

A F B Cl

C Na

+ D Al

3+

6 The information below describes an element, T.

Melting point is 44OC Produces acidic oxides Monatomic in solid

Element Tcould be

A Fluorine C Magnesium

B Sodium D Phosphorus

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

A Atomic size

B Ionization energy

C Electric conductivity

D Boiling point

8 Which of the following molecules will not form a hydrogen bond with another similar

molecule?

A C6H5OH

B CH3NH2

C CH3CHO

D NH3

Proton number

Property

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4

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 Carbon C Neon

B Magnesium D Oxygen

10 The shape of a molecule depends on the following factors, except

A The number of lone-pair electrons

B The number of bond-pair electrons

C The number of attractions between the electron orbitals

D The number of atoms bonded to the central atom

11 A chemist sketched a graph as shown below.

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

A Esterification C Sulphonation

B Nitration D Neutralization

12 Which of the following is true about the half life of a first order reaction?

A The half life is longer for a catalyzed reaction.

B The half life is shorter when pressure increase.

C After the fourth half life, the percentage of the remaining element

is 6.25% of the original quantity.

D The half life is influenced by the concentration of the reactant.

Time

Rate of reaction

Reactant

Products

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5

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

below.

If the temperature of an equilibrium mixture of the gases is increased at constant pressure ,

the volume of the mixture will

A Increase, but only because of a shift of equilibrium towards the right

B Increase, both because of a shift of equilibrium towards the right and also because of

thermal expansion.

C Stay the same, because any thermal expansion could be exactly counteract any

thermal expansion

D Decrease, because a shift of equilibrium towards the left would more than counteract

any thermal expansion.

14 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?

compound solubility product

A AgBr 5 x 10-13

mol2dm

-6

B AgCl

2 x 10-10

mol2dm

-6

C AgIO3 2 x 10-8

mol2

dm-6

D Ag2SO4 2 x 10

-5mol

3dm

-9

15 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 50%

B 62%

C 76%

D 100%

16 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 Electrolysis of aqueous magnesium chloride

B Electrolysis of molten magnesium chloride

C Electrolysis of molten magnesium oxide

D Reduction of magnesium oxide with carbon

N2O4 (g) 2NO2 (g) Ho

= + 57.2 kJmol-1

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6

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 2.8 dm3

B 5.6 dm3

C 8.4 dm3

D 11.2 dm3

18 Which one of the following equation correctly defines the enthalpy change of formation

of carbon monoxide?

A C(s) + O2(g) CO(g)

B C(s) + O (g) CO(g)

C C(g) + O2(g) CO(g)

D C(s) + CO2(g) 2CO(g)

19 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) + H2(g) C2H6(g)

A -137 kJmol-1

B -33 kJmol-1

C +33 kJmol-1

D 137 kJmol-1

20 Four isomers of C6H12 are shown below.

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

A 1 and 2 C 1 and 4

B 1 and 3 D 2 and 4

CH

CH

C C

H C2H5

CH3 C2H5

C

H CH3

C2H5 H

CH3CH3

C C

C2H5 CH3

H CH3

C C

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8

25 Aldehyde and ketone are produced through catalytic oxidation of alkenes. One example of thereaction 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 CH3CH2CHO

B CH3CH2CH2CHO

C CH3COCH2CH3

D CH2COCH3

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

is as follows.

What could Q be?

27. Why is ethanoic acid a stronger acid in liquid ammonia than in water?

A Ammonia is a stronger base than water.

B The molecules of ethanoic acid form a hydrogen bond with water.

C Ethanoic acid dissolves better in liquid ammonia than water.

D Ethanoic acid has a higher enthalpy of hydration.

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

A Ethanol is a polar molecule whereas ethyl ethanoate is not polar.

B Ethanol is not polar whereas ethyl ethanoate is polar.

C Hydrogen bonds are formed between the ethanol and water molecules.

D Hydrogen bonds are formed between ethyl ethanoate molecules.

A

B

C

D

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9

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

30.

Reagent R is most probably

A Ammonia nitrateB Ethanamide

C Alcoholic ammonia

D Methylamine

31 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?

32 The scheme shows

A cationic polymerisation

B anionic polymerisation

C coordination polymerisation

D condensation polymerization

A C

B D

A C

B D

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10

33 Which of the following forms an ionic hydride?A Sodium

B Silicon

C Sulphur

D Chlorine

34 Aqueous aluminium chlorine has a pH less than 7 becauseA the charge density of the aluminium ion is high.

B the aluminium ion undergoes hydrolysis

C aluminium chloride undergoes partial dissociation in water.

D aluminium chloride is a covalent compound.

35 A tetrachloride of Group 14, XCl4 has the following properties.(i) It is easily hydrolysed.(ii) Unstable to heat.(iii) Decomposes at room temperature according to the equation

XCl4 XCl2 + Cl2X could be

A germanium

B carbon

C silicon

D lead

36 Which of the following best explain the decreasing thermal stability of the chlorides andoxides in the oxidation state of +4 of the Group 14 elements (carbon to lead ) in the Periodic

Table when descending the group?

A The bond energy increases.

B The first and second ionization energy decreases.

C The standard electrode potential decreases.

D Presence of the inert pair effect of the s orbital electrons.

37 Which of the following is correct regarding dinitrogen tetroxide, N2O4?A It is polar.

B It has a V shape

C It is produced from NO2.

D It contains one unpaired electron.

38 Which of the following is true with regards to the ammonia molecule?A It is non-polar molecule.

B It has a trigonal planar shape

C The H N H bond angle is 107o.

D It contains two lone pairs of electrons.

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11

39 The scheme below shows the reactions between potassium iodide with hot concentratedsulphuric acid, and with aqueous siver nitrate, as well as the solubility of the precipitate Yin

concentrated aqueous ammonia.

Which of the following is correct with regards to the colour of vapourX, colour of the

precipitate Y, and the solubility ofY, in concentrated ammonia?

40 Which of the following statements helps to explain why nickel can act as a catalyst in thehydrogenation of ethene at 200

oC according to the equation :

H2C = CH2 (g) + H2 (g) CH3CH3 (g)

A Nickel can exhibits variable oxidation states.

B Nickel has dorbitals that can form temporary bonds.

C Nickel can form stable intermediate with the reactants.

D Nickel is neutral in the hydrogenation process of H2C = CH2 .

Colour ofX Colour ofY Solubility ofY, in conc. NH3

A Brown White Soluble

B Purple Yellow Soluble

C Purple White Insoluble

D Purple Yellow Insoluble

Conc. H SOVa ourX

Product

heat

Conc. NHAgNO3 (aq)

KI s

Precipitate Y

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12

Section B

For questions41 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.

A 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.

41 Which of the following depends on the number of solute particles in a given mass of solvent?

1 Elevation of boiling point of solvent

2 Depression of freezing point of solvent

3 Vapor pressure of solute

42 Hydroxyapatite, Ca5(PO4)3OH is the main constituent of tooth enamel . In the presence of

saliva, the following equilibria exist.

Which of the following statements help to explain why tooth enamel is dissolved more

readily when saliva is acidic?

1 The hydroxide ions are neutralised by the acid2 The phosphate ion PO42- (aq) accepts H+ (aq)3 Calcium ions react with acids

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

Acid Ka (moldm-3

)

phenylethanoic acid 4.90 x 10-5

3-hydroxybenzoic acid 8.32 x 10-5

2-chlorobutanoic acid 1.15 x 10-3

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

1 Ka for 2,2-dichlorobutanoic acid is greater than Ka for 2-chlorobutanoic acid2 [H+] in 1.00 moldm-3phenylethanoic acid solution is 4.90 x 10-53

3-hydroxybenzoic acid is the strongest acid

Ca5(PO4)3OH (s) 5Ca2+

(aq) + 3PO43-

(aq) + OH-aq)

HPO42-

(aq) H+

(aq) + PO43-

(aq)

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13

44 Under which of the following conditions would the Partition Law not hold?

1 When the solutions are concentrated2 When the solute dissociate or associate in the solvents3 When the temperature changes

45 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 carbonatesof the Group 2 elements (beryllium to barium) when descending the group?

1 When the solutions are concentrated2 When the solute dissociate or associate in the solvents3 When the temperature changes

48 Which of the following aqueous cations would give a precipitate when excess ammonia isadded to it?

1 Al3+

2 Zn2+

3 Cu2+

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14

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

1 is to separate the anode compartment from the cathode compartment.2 is to prevent the reaction between chlorine and sodium hydroxide produced.3 Is to act as catalyst to speed up the electrolysis process.

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

regards to the complex salt?

1 The ratio ofx toy in the formula of the salt is 2:1.2 The name of the complex salt is diaquatetraamminenickel(II) chloride.3 The cis isimer of the complex is optically active.

END OF QUESTION PAPER

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CONFIDENTIAL*

STPM962/2 [Turn over

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

Name : NRIC :

JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR















JABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJARJABATAN PELAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAR








JABATAN PENLAJARAN ERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA

Instructions to candidates :

This question paper consists of 11 printed pages

Answerallthe 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 examiners use

Section Marks Marks

Obtained

A

1 10

2 10

3 10

4 10

40

B

5 15

6 15

7 15

8 15

9 15

10 15

60

TOTAL 100

Two and a half hours

OTI 2

STPM 2009

JABATAN PELAJARAN

NEGERI TERENGGANU

962 / 2

CHEMISTRY

PAPER 2

STRUCTURE AND ESSAY

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CONFIDENTIAL *



2

Section A (40 Marks)

Answerall 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.

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

[2 marks](b) Graph against p for 1.0 mol H2 and CO2 at 273K is shown below:

(i) Explain why carbon dioxide behaves like an ideal gas at low pressure.

[1 mark]

Ideal gas

CO2

H2

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3

(ii) 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 andB.

(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.

[3 marks]

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4

(iii) Using the result obtained in(ii),write the Nernst equation of the above cellreaction.

[1 mark]

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

[5 marks]

Energy

Ca2+(g) + S2-(g)

Ca s + S s

CaS s

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5

(ii) 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-1The 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

[4 marks]

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7

On the axes below,sketch the general trend for each property of the elements or theircompound the third period of the Periodic Table. No scale is given for the verticalaxis.Your sketch is expected to be clear but only qualitative.Expalain the changes shown.

[1 mark]

Explanation

.

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

..

[3 marks]

(b) Chromium (proton number = 24) is a d-block element. A lot of chromium compoundare 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]

.

SMg

Melting point of oxides (o

C)

PSiAlNa

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8

5 (a) State the difference between the hydrogen emission spectrum and a spectrumproduced 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 theground states electronic configuration of an atom.

(i) State the rule and principles.[3 marks]

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

(d) (i) What is meant by the atomic radius of an element?

[ 1 mark](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]

6 (a) Predict the shape of the NH3 molecules and NH4+ ions , explain the differences intheir bond angel.

[4 marks](b) Draw a labeled diagram showing the overlapping of orbitals in

(i) H2O [2 marks](ii) C2H4

[2 marks](c) The boiling point of H2O is higher than HF.Explain.

[2 marks]

(d) The rate of decomposition of acidic hydrogen peroxide can be analysed throughtitration. Hydrogen peroxide samples with a fixed volume are taken at specific timesand were titrated with potassium manganate(IV) solution. The titration results are as

follows:

Time/min 0 10 20 30

Volume of KMnO4(aq)/cm3 45.5 27.4 16.4 9.9

(i) Determine the half-life of this reaction by plotting the graph, using the datafrom the table above.

[4 marks](ii) What is the order of this reaction?

[1 mark]

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9

7 (a) State Le Chateliers principle.[2 marks]

Referring to the equilibrium

(b) Explain

(i) the effect on the yield of NO when pressure on equilibrium mixture isincreased

(ii) the effect on equilibrium constant, Kc when temperature on the equilibriummixture is decreased.

[4 marks]

(c) If 0.40 mol of NH3 and 0.50 mol of O2 in a 1 dm3 container is allowed to react in thepresence 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]

Given that the reaction is second order.

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

[2 marks]

(e) If the graph of]A[

1versus time is as given below.

Calculate(i) the rate constant

(ii) the initial concentration ofA

[3 marks]

(f) Suggest the mechanism for the reaction[2 marks]

A B

A B

4NH3(g) + 5O2(g) 4NO(g) + 6H2O(g) H = 908 kJ mol1

t / min

]A[

1/ mol1 dm3

200

2.0

12.

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10

8 (a) Describe and explain the variation in boiling point of the tetrachlorides of Group 14from Carbon to lead

[4 marks]

(b) How and why do CCl4 and SiCl4 differ in their reaction with water? Include,in youranswer any reaction that occurs.

[4 marks]

(c) Suggest a use of each element or compound below, and explain how each of the usesis related to physical or chemical properties and structure.

(i) Silicon(ii) Silicon (IV) oxide(iii) Carbon dioxide

[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 whenchoosing a site for an aluminium factory.State one adverse effect on the environment as a result of the extraction process ofaluminium.

[4 marks]

9 (a) An alkene, C4H8 reacts with hydrogen chloride to produce a compound, C4H9Cl, drawthe structure of the alkene and the chloro-compound.

[2 marks]

(b) With reference to the reaction scheme below.:

(i) Identify compounds A to E.

(ii) Name the reagent used in step I.

(iii) Give an important use for compound E. [7 marks]

NaOHreflux

A C2H6

B

180oC Conc.H2SO4

C DBr2/CCl4 NaOH

E

Cl2/ light

Reflux

Step 1

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11

(c) Suggest how you would differentiate the following pairs of compounds by chemicalmeans.

(i) 1-iodohexane and 1-chlorohexane

(ii) chlorocyclohexane and chlorohexane

(iii) 1-chloro-1- butane and 1- chlorobutane [6 marks]

10 (a) The structural formulae of two amines are shown below.

Which is the stronger base? Explain[2 marks]

(b) Suggest ,with reasons.how the basicity of 3,4-difluorophenylamine might camparewith that of phenylamine.

[2 marks]

(c) Ziegler-Natta catalyst is a mixture of titanium(IV) chloride, TiCl4 andtriethylaluminium, Al(CH3CH2)3, Explain the addition polymerisation mechanismwith the ziegler-Natta catalyst to produce poly(ethene).

[6 marks]

(d) Give two advantages of addition polymerisation with the Ziegler-Natta catalystcampared 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 thesecompound? Explain.

[2 marks]END OF QUESTION PAPER

Tetrahyroquinoline

Tetrahydroisoquinoline

3,4-Difluorophenylamine

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Name : NRIC :

JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA



JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAJABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA











JABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJAJABATAN PELAJARAN TERENGGANUJABATANPELAJARAN TERENGGANU JABATANPELAJA








MARKING SCHEME

This answer paper consists of 17 printed pages

CHEMISTRY

PAPER 1 & 2

TRIAL962/1

JABATAN PELAJARAN

NEGERI TERENGGANU

TRIAL EXAMINATION 2009

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OTI 2 2009 STPM

Marking scheme OTI 22009

2

STPM CHEMISTRY 962/1

OTI 2 2009

MARKING SCHEME PAPER 1

QuestionNo.

Answer Explanation

1 A These are the isotopes of iron. Different isotopes have different numbers ofneutron

2 D Of the 4 gasses given hydrogen gas is most likely to exhibit ideal behavior.Refer to any graph of (pV/nRT) againstp.

3 D Carbon dioxide cannot be solidified at 1.0 atm if the temperature is greatlyreduced. At 1.0 atm CO2 exists in both solid and gaseous forms.

4 C Actual electronic arrangement is 1s2 2s2 2p6 3s2 3p1. Total number ofelectron is 13. Thus the proton number is 13

5 C Na+ is the biggest as it has the smallest number of nuclear charge. Thesmaller the nuclear charge, the bigger the ionic size.

6 D Only phosphorus can exist as monatomic solid with acidic properties in itsoxides.

7 C Across period 3 from left to right, conductivity increases for the first 3elements, then starts to decrease as the elements become metalloid, anddecreases further as elements are non-metals.

8 C In the CH3CHO molecule, hydrogen atom is bonded to carbon not oxygen.So no intermolecular hydrogen bonds.

9 B No energy gap between the two bands, so it belongs to a metal, which ismagnesium.

10 C There are only repulsive forces exist between electron orbitals. So the lonepair electrons push each other so that the angle between them is maximized.

11 A The graph is reversible reaction. The rate of the forward reaction is equal tothe rate of the backward reaction over time. The formation of ester is areversible reaction.

12 C e.g.: if the original sample = 100g100g 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

13B

Since the forward reaction is endothermic, an increase in temperature shiftsthe equilibrium to the right according to Le Chateliers principle, by

absorbing the excess heat. In the case, more gas particles are produced andthere is an increase in volume. Furthermore, heating will also cause the gasesto expand.

14A

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

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OTI 2 2009 STPM


3

Question

No.

Answer Explanation

15B

mB = MB x PoBmW MW x PoW

mB = 156.6 x (101 x 85)100 18 x 85

= 163.66

% bromobenzene = 163.66 x 100(1663.66 + 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. Afeasible way would be the electrolysis of molten Mg2+ , in this case, MgCl2(MgCl2 has a lower m.p. than MgO).

17A

Quantity of electricity used = I x t= 8 x (100 x 60)= 48000 C

Amount of electrons passed = 48000C96000 Cmol-1= 0.5 mol

Amount of O2 evolved = 0.54

= 0.125 mol

Volume of O2 evolved = 0.125 x 22.4= 2.8 dm3

18A The enthalpy change of formation of CO is the enthalpy change when 1mol of gaseous CO is formed from its constituent elements, that is C and O2,

at their standard states.

19A

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

20A

For cis-trans isomers, 2 different groups must be bonded to the same C at thedouble bond.

B : 1 and 3 are identical

C : 1 and 4 are structural isomersD : 2 and 4 are structural isomers

2O2-(l) O2(g) + 4e

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OTI 2 2009 STPM


4

Question

No.

Answer Explanation

21C Upon reacting with Br2 , but-1- ene gives 1,2- dibromobutane and

but -2-ene gives 2,3- dibromobutane.22

BBeing an alkene, hex-1-ene undergoes electrophilic addition readily with Br2in CCl4 and decolourised it. Methylbenzene is unable to do so.

CH3(CH2)3CH=CH2 + Br2 CH3(CH3)3CHBrCH2Br

23 A

24 A Remember: Ethanoyl chloride (acyl chloride) will react with alcohols butnot with carboxylic acids.

25 B CH3CH2COOH All carbonyl compounds, which are aldehyde and ketonereact with 2,4-dinitrophenyihy- drazine to form orange precipitate that has ahigh melting point.

26 A Ethanoic acid is a weak acid and it partially ionises in water to producehydroxonium 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 acidmolecules will ionise. Thus H+ ions are produced are the strength of ethanoicacid will increase. Thus ethanoic is a stronger acid in liquid ammonia than inwater.

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 f ormhydrogen bonds with water, thus it is less soluble in water

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OTI 2 2009 STPM


5

Question

No.

Answer Explanation

29 C

30 D chlorideAn aromatic amine with an amino group at its side chain will have similarchemical properties as an aliphatic amine.

31D

At pH 2, an acidic solution and 2-aminopropanoic acid (alanine)will existas positive ions.

32 BThe reaction results in a nucleophilic addition to the double bond and theanionic polymerisation process takes place.

33 ANaH ion, SiH4 - covalent, H2S covalent, HCl covalent.The sodium atom wiyh the biggest size among the four elements hasthe lowest ionization energy and can lose electron readily to formionic compound.

34 AAluminium is a amphoteric. It si soluble in aqueous sodium

hydroxide.Al2O3 (p) + 2OH- (aq) + 3H2O(l) 2[(OH)4]- (aq)35 D

XCl4 decomposes at room temperature showing that the X-Cl bond isvery weak. Hence, X must have the biggest size in Group 14.

PbCl4(l) PbCl2 (s) + Cl2 (g)

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

becomes less stable.

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OTI 2 2009 STPM


6

Question

No.

Answer Explanation

37 C 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 nitrogenatom. 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 The lone pair electrons in NH3 pushes the three bonding pairs closer toone another. Hence, its bond angle is slightly less than that of a perfecttetrahedron, 109.5o .

39 D KI reacts with H2SO4 to produce iodine, which is a purple fume.KI + H2SO4 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)

AgI is insoluble in either dilute or concentrated ammonia.40 B Heterogeneous catalyst uses their empty d orbitals to form temporary bonds

with the reacting molecules. This process is known as adsorption.41 B 1 Elevation of boiling point of solvent

2 Depression of freezing point of solvent42

B(1,2)According to Le Chatliers Principle,When OH- ions are neutralized by the acid, position of eq will shift to theright, 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.

43A( 1 )

Halogen is an donating group which decreases the acid strength.( Ka isgreater)

44D(1,2,3)

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

45 D The Grignard reagent has the general formula, RMgX. With ketones, a

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OTI 2 2009 STPM


7

Question

No.

Answer Explanation

tertiary alcohol is produced.Remember: The CMg and CLi bonds are very polar. When either theCMg or the CCl bonds undergoes fission, the carbon acts

as a nucleophile

46 A To form a diazonium salt, nitric(III) acid must react with a primary aromaticamine solution at a temperature of 0 5C. 2-methylphenylamine, is a

primary aromatic amine.

47 A Going down group 2, the size of the cation increases causing the polarizingpower to decrease. Statement 2 only indicates that the oxides are more stablethan the carbonates. It does not explain about the stability trend of thecarbonates.

48 C Zn(OH)2 and Cu(OH)2 are soluble in excess ammonia.49 B50 B 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 : 1The complex does not contain polydentate ligands. Hence, it cannot exhibitsoptical isomerism.

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8

STPM CHEMISTRY

OTI 2 2009/TRIAL EXAM

MARKING SCHEME

PAPER 2

SECTION A ( Structured Question )

QUESTION

NOSUGGESTED ANSWERS SUGGESTED

MARKS1(a)(i) The element X contains isotopes. 1

1(a)(ii) Lets the percentage abundance of79

X = x%

Percentage abundance of81

X = (100-x)%

79.99 =

X = 50.5

Percentage abundance of isotopes79

X = 50.5%Percentage abundance of isotopes

81X = 49.5%

1or1

1

1

Any 2

1(a)(iii)

Axis labeled

and unit1

Draw a correct

peak1

1(b)(i)

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

11

1(b)(ii) Positive deviation 1

1(b)(iii)

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)

11

Total 10

79 80 81 m/e

Abundance(%)

50.5

49.5

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9

QUESTION


MARKS2 (a) (i) Zn(s) + 2Ag

+(aq) Zn 2+(aq) + 2Ag(s) 1

2 (a) (ii) Half cell reaction E0/V

Zn2+

(aq) + 2e Zn(s) -0.762Ag

+(aq) + 2e 2Ag(s) +0.8

Zn(s) + 2Ag+

(aq) Zn2+(aq) + 2Ag(s)E.m.f. of cell = 0.80 + 0.76 = 1.56 V

11

1

2 (a) (iii) EcellEceii - 0.059 log [Zn2+

]

2 [Ag]2

1

2 (b) (i)

2 (b) (ii) -487 = 178 + 279 + (590 + 1150) + 337 + Lattice energy

Lattice energy = -3021 kJ mol-1

5

For every

single level

energyshown,one

mark will be

given

1+1

Total 10

3 (a) (i) CH3COCl + CH3CH2CH2OH CH3COO CH2CH2CH3 + HClPropyl ethanoate

1

1

3 (a) (ii) CH3COCl + C6H5NH2 CH3CONH C6H5 + HClN-phenyl ethanamide

1

1

3 (b) Heat with dilute sulphuric acid.

CH3CONH C6H5 + H2O CH3COOH + C6H5NH21

3 (c) Structural formulae of the products :

HOCH2CHOH and NaOOCCH2COONa

CH3

1+1

3 (d) (i) Heat 2-hydroxybenzoic acid with ethanoyl chloride. 1

1

3 (d) (ii) X is aspirin. It is an analgesic. 1

Total 10

Latice energy

CaS(s)

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10

QUESTION


MARKS4 (a) (i) Dinitrogen oxide, N2O 1

4 (a) (ii) NH4NO3(s) N2O(g) + 2H2O(l) 1

4 (b)

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

1

4 (c) (i) 1

4 (c) (ii) 3delectrons 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

Mg

Melting point of oxides

P SSiAlNa

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11

QUESTION


MARKS5(a) The hydrogen emission spectrum consist of discrete lines

whereas the spectrum produced by the tungsten filament bulb is a

continuos spectrum.

11

5(b) 1s,2s,2px,2pyThe difference between 1s and 2s is thatthe size of 2s is bigger than 1s.orThe difference between 2s and 2p is that2s is spherical but that 2p is dumb-bell shape.

1

1or1

Max 2

...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.

1

1

1

5(c) (ii) Number of electrons in O2-

ion = 8+2=10Step 1: Apply Pauli exclusion principle and Aufbau principle.Fill 1s

orbital with two electrons.

1s 2s 2pStep 2:Fill 2s orbital with two electrons

1s 2s 2pStep 3: Apply Hund`s rule.

Fill 2px,and 2py orbitals wih three electrons. The electrons mustbe in parallel spins.

1s 2s 2pStep 4: Fill the remaining three electrons in 2px,2py and 2pzorbitals .

Each pair of electrons must be in parallel spins.

1s 2s 2p

1

1

1

1Describe or

show the filling

using a

diagramAny 3

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12

QUESTION


MARKS5(d) (i) Atomic radius is defined as half the distance between the nuclei of two

closest and identical atoms.

1

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.

111

1

Total 15

6 (a) NH3Valence electron, N : 5e

3H : 3e

-------------8e 3 bond pair, 1 lone pair

-------------

..N

Or trigonal pyramidal1070

NH4+

Valence electron, N : 5e4H : 4e

Positive charge : -1e(less 1 electron)

-------------8e 4 bond pair, no lone pair

--------------

Or tetrahedral

109.5)

The bond angle of NH3 is 1070

wheares the bond angle of NH4+

1

Draw or state

the shape1

1

Draw or state

the shape1

Any 4

H H H

N

H+

H H H

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13

QUESTION


MARKS6 (b) (i) H2O

..

Overlapping

1

label

1

6 (b) (ii)C2H4

Overlapping1

label1

6 (c) Boiling point of H2O is higher than HF becauseeach HF molecule forms 2 intermolecular hydrogen bondscompared to 4 intermolecular hydrogen bonds formed by each H2O

molecule.

11

6 (d) (i)

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

Label the axis

and unit1

Plot the graph1+1

Indicate on thegraph

t1/2

1

H(1 s)

H(1 s)

sp3

orbitals

H(1s)

H(1s)

H(1s)

H(1s)

C C

Volume of KMnO4

10 20 30 t/min

40

30

20

10

O

t1/2= 13.5 t1/2= 13.5

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14

QUESTION


MARKS6 (d) (ii) From the graph, half life doesnot depend on the concentration of

hydrogen peroxide. Thus, the reaction is first order.1

Total 15

7(a) When an equilibrium is disturbed then equilibrium will shift in thedirection that will reduce the effect of the disturbance.

2 m

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.

1 m

1 m

7(b)(ii) Value of Kc increases.

The forward reaction is exothermic, the Kc value decreases with

increase in temperature.

1 m

1 m

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

1.5xx1.25x0.5x0.4

x

+++

= 30 %

x =0.29 mol

1 m

1 m

7(d) (ii) (ii)

]

7(e)(i)

]A[

1= kt +

0]A[

1

k =25

0.20.12 = 0.40 mol

1dm

3min

1

1 m

1 m

7(e)(ii)

0]A[

1= 2.0

[A]0 = 0.50 mol dm3 1m

7(f) A + A M slow step

M 2B fast step

1 m

1 m

Total 15

Rat

[A

0

A

t0

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15

QUESTION


MARKS8 (a) Boiling point of tetrachlorides increases down the group

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

Molecular size increases from top to bottom.

Strength of van der Waals forces increases down the group.

1

1

1

1

8 (b) SiC14 undergoes hydrolysis whereas CCI4 does not.

This is because the Si atom has empty dorbitals which can be attacked

by lone pair electrons from water molecules. The product of

hydrolysis is silicon(IV) oxide and hydrochloric acid.

, C atom in tetrachioromethane does not contain empty

dorbitals, hence does not undergo hydrolysis.

1

1

11

8 (c) (i) Semiconductor

Semimetal, electrical conductivity increases when temperature is

raised.

Ceramic

The SiO covalent bond in the giant covalent network is strong.

In fire extinguishers. Does not support combustion

1

1

1

8 (d) 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.

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 ofaluminium oxide and cryolite.

1

1

1

1

Total 15

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16

QUESTION


MARKS

9(a) CH3-CH=CH-CH3

CH3- CH- CH

2-CH

3

Cl

2m

9(b) A: CH3CH2Cl D : CH2Br- CH2Br

B : CH3CH2OH E : CH2OH CH2OH

C : CH2=CH2 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

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17

QUESTION


MARKS10 (a) Tetrahydroisoquinoline is the stronger base. In tetrahydroquinoline, the

unshared electron pair is delocalised into the aromatic ring, making it

less available to accept a proton, whereas tetrahydroisoquinoline

resembles an alkylamine.

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,

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.

The process is terminated when a hydrogen atom is added to a titanium

atom, and the poly(ethene) chain is separated from titanium.

1

1

1

1

1

1

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.

1

1+1

10 (e) Proteins and polypeptides.

Nylon has peptide linkages, CONH, which are also found in

proteins and polypeptides.

1

1

Total 15

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