SSC FSFE - CHEM 2012 QP.pdf

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MINISTRY OF EDUCATION

FIJI SEVENTH FORM CERTIFICATE EXAMINATION 2012

CHEMISTRY PAPER 1

Time Allowed: Three Hours

(An extra ten minutes is allowed for reading this paper.)

INSTRUCTIONS

1. Write all your answers in the Answer Book provided.

2. Write your Index Number on the front page and inside the back flap of the Answer Book.

3. If you require more paper, ask the supervisor for extra sheets. Tie these inside the Answer Book at the appropriate places.

4. You may use a calculator, provided it is silent, battery-operated and non-programmable. In Sections B and C, working should be shown in the questions involving calculations.

5. There are three sections in this paper. All the sections are compulsory.

Note : A Periodic Table of Elements is provided for your use during this examination. Both the atomic number and the relative atomic mass for each element are given.

SUMMARY OF QUESTIONS

Section Guidelines Total

Mark

Suggested Time

A

There are twenty-four multiple-choice questions. All the questions are compulsory.

24 43 minutes

B There are twelve questions.

All the questions are compulsory.

36 65 minutes

C There are five questions.

All the questions are compulsory.

40 72 minutes

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SECTION A

[24 marks]

The multiple-choice questions in this section are all compulsory. Each question is worth 1 mark.

INSTRUCTIONS FOR MULTIPLE – CHOICE QUESTIONS

1. In your Answer Book, circle the letter which represents the best answer. If you change your mind, put a line through your first choice and circle the letter of your next choice.

For example:

2. If you change your mind again and like your first answer better, put a line through your second circle and tick () your first answer.

For example:

3. No mark will be given if you circle more than one letter for a question.

1. Which quantum number specifies the location and energy of an electron?

A. Principal B. Secondary C. Magnetic D. Spin

2. Suppose an electron in an atom has the following set of quantum numbers:

Which set of quantum numbers given below is impossible for another electron in the same atom?

A. n = 2, l = 0, ml = 0, ms = +½

B. n = 2, l = 0, ml = 0, ms = – ½

C. n = 2, l = –1, ml = –1, ms = +½

D. n = 2, l = 1, ml = –1, ms = – ½

Turn Over

© MINISTRY OF EDUCATION, FSFCE 2012: CHEMISTRY.

12 A B C D



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3.

3. A molecule is said to be polar if it

A. consists of positive and negative ions. B. is composed of an odd number of atoms.

C. consists of atoms differing widely in electron attracting power. D. takes up a preferred orientation when placed in an electric field.

4. How many pi bond(s) and sigma bonds are there in an ethyne molecule?

A. 1 pi bond and 2 sigma bonds B. 1 pi bond and 3 sigma bonds C. 2 pi bonds and 3 sigma bonds D. 2 pi bonds and 2 sigma bonds

5. According to the kinetic molecular theory, the particles of an ideal gas

A. have no potential energy.

B. have strong intermolecular forces.

C. are arranged in regular repeated geometric pattern. D. are separated by great distances compared to their size.

6. 40 cm3of an ideal gas rises in temperature from 30º C to 60º C; at the same time the pressure of the gas is halved. The volume occupied by the gas at the higher temperature is about

A. 160 cm3

B. 90 cm3 C. 80 cm3 D. 40 cm3

7. The following are characteristic properties of some elements.

I. They form basic oxides.

II. They are strong oxidising agents.

III. They have relatively low ionisation energies. IV. They have relatively high electron affinities.

Which of the above properties are true for Alkali metals?

A. I and II B. I and III C. I, II and IV D. II, III and IV

Turn Over

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8. When solid hydrated copper sulphate is heated it produces steam and white anhydrous copper sulphate. This compound is white because

A. copper has an electron configuration of [Ar]3d104s1. B. the copper ion in copper sulphate has a full d-orbital. C. the copper ions are reduced to Cu+ ions.

D. the copper ion no longer has ligands.

9. An element X is a good conductor of electricity. It forms an oxide which dissolves in water and a chloride which dissolves in organic solvents.

X is most likely to be

A. nickel. B. lithium. C. aluminium. D. phosphorus.

10. When a bomb calorimeter is used to determine the heat of reaction, the property of the system under investigation that is most likely to remain constant is

A. volume. B. pressure. C. temperature.

D. number of molecules.

11. The equation that summarises the lattice energy of sodium fluoride is

A. Na(g) + ½ F2(g) NaF(s)

B. Na(s) + ½ F2(g) NaF(s)

C. Na(g) + F(g) NaF(s)

D. Na+(g) + F–(g) NaF(s)

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5.

12. The structures below show four isomers of C6H12.

CH3 CH3 CH3 C2H5 C2H5 H C2H5 CH3

C ═ C C ═ C C ═ C C ═ C

H C2H5 H CH3 CH3 CH3 H CH3

I. II. III. IV.

In which pair is the members cis-trans isomers of each other?

A. I and II B. I and III C. I and IV D. II and IV

13. Propylbutanoate can be prepared from a reaction involving concentrated H2SO4 with

A. CH3CH2CH2CH2OH and CH3CH2CH2 CH2COOH.

B. CH3CH2CH2OH and CH3CH2CH2 CH2COOH.

C. CH3CH2CH2OH and CH3CH2CH2COOH.

D. CH3CH2CH2CH2OH and CH3CH2COOH.

14. The following liquids have the same number of electrons in each molecule. Which one is likely to have the lowest boiling point?

A.

B.

C. CH3 CH2 CH2 CH2 CH3

D. CH3 CH2 CH2 C OH

Turn Over CH3

CH3

CH3 C CH3

CH3

CH3 C CH2 CH3

H

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15. Which of the following amines does not have hydrogen bonds between its molecules in the liquid state?

A. (CH3)2CHCH2NH2

B. (CH3)2 NCH2CH3

C. CH3CH2NHCH2CH3

D. CH3CH2CH2CH2NH2

16. The IUPAC name of (CH3)2CHCH = CHCH3 is

A. 4 – methyl – 2 – pentene. B. 1 – isopropylpropene.

C. 1, 1 – dimethyl – 2 – butene. D. 1, 2 – methyl – isopropylethene.

17. The reaction : C3H7Cl + C2H5 0 – C3H7OC2H5 + CI – is

A. an elimination reaction.

B. a nucleophilic substitution reaction. C. a nucleophilic addition reaction. D. an electrophilic substitution reaction.

18. Which of the following reacts with ethanol to form the ethoxide ion?

A. Na(s)

B. Na2O(s)

C. NaCl(aq)

D. NaOH(aq)

19. Two salt solutions were mixed in a trial experiment. The solubility product, Ksp for the

trial experiment was calculated to be 2.0 x 10–9. The theoretical Ksp value was 1.0 x 10 –10

.

Using the above information, which of the following is true?

.

Ksp comparison Outcome

A. trial Ksp < Ksp no precipitate forms

B. trial Ksp > Ksp no precipitate forms

C. trial Ksp > Ksp precipitate forms

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7.

20. Which of the following titrations always results in pH = 7.0 at equivalence point?

A. A weak acid is titrated with a weak base. B. A weak acid is titrated with a strong base. C. A strong acid is titrated with a strong base. D. A strong acid is titrated with a weak base.

21. At 20.0 º C water has the ionic product, Kw of 6.807 x 1015.

The pH of water at this temperature is

A. 6.667 B. 6.920 C. 7.000 D. 7.084

22. Consider a cell operating by connecting the two half–cells given below with a salt bridge:

Cr3+ 3e– Cr Eo = – 0.74 V Ag + e– Ag Eo = + 0.80 V

Which of the following statements is correct?

A. Chromium is reduced. B. Silver is deposited.

C. Electrons are transferred through the salt bridge. D. Electrons are transferred from silver to chromium.

23. The standard electrode potentials of three reactions are as follows:

Zn2 + 2e– Zn Eo = – 0.76 V

Fe2 + 2e– Fe Eo = – 0.44 V

Fe3 + e– Fe2 Eº = + 0.76 V

The voltage of a cell involving zinc and iron was + 0.32 V. Which cell notation represents this cell?

A. Zn(s) Zn2+(aq) Fe2+(aq) Fe(s)

B. Zn(s) Zn2+(aq) Fe3+(aq) Fe 2+(aq)

C. Fe(s) Fe 2+(aq) Zn2+(aq) Zn(s)

D. Fe2+(aq) Fe3+(aq ) Zn2+(aq) Zn(s)

Turn Over

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24. An iron pipe, when buried in the ground, may be prevented from corroding by being joined to a piece of magnesium which is also buried as shown in the diagram below.

iron pipe surface

magnesium

ground

Which statement provides the best explanation of this effect?

A. Magnesium atoms take the place of the iron atoms lost by the corroding pipe.

B. Magnesium reacts with water to form a protective coating of magnesium hydroxide on the iron pipe

C. Electrons from the corroded magnesium flow through the wire to the iron preventing the iron atoms from losing their own electrons.

D. Electrons from the iron flow through the wire to the magnesium, leaving a protective coating of iron oxide on the pipe.

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9.

SECTION B

[36 marks]

The twelve questions in this section are all compulsory. Each question is worth 3 marks.

QUESTION 1

(a) Provided in the list below are different types of forces of interactions that commonly occur between species.

ion-dipole forces hydrogen bonding

dipole-dipole forces induced dipole forces

dipole-induced dipole ion-induced dipole forces

Select the correct type of forces that will exist between the following pairs of species:

(i) HBr and H2S

(ii) Cl2 and CBr4

(iii) Na+and H2O

(iv) NH3 and C6H6

(2 marks)

(b) Water molecules have a V-shaped structure and this allows very good solvent properties. Explain why water would not be a good solvent if water molecules

were linear. (1 mark)

QUESTION 2

The following graphs show trends in values observed for the quantities specified below.

Identify the graph that represents each of the following trends and give a reason for your choice.

(a) First ionisation energies of Mg, Ca, Sr and Ba (1 mark)

(b) First four ionisation energies of K (1 mark)

(c) Atomic radii of Mg, Ca, Sr and Ba (1 mark)

Ar b itra ry v er tical sca le • A B C D

Four point horizontal scale

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QUESTION 3

(a) Hydrogen peroxide decomposes according to the following equation:

2H2O2(aq) 2H2O₍_₎ + O2(g)

Calculate the volume of oxygen produced at 30oC and 91 kPa when 10 g of

hydrogen peroxide decomposes. [R = 8.314 Jmol–1K–1] (2 marks)

(b) Calculate the molality of a 44.6 percent by mass aqueous solution of barium chloride.

The molar mass of barium chloride is 208 g/mol. (1 mark)

QUESTION 4

Water combines with titanium ion, Ti2+ to form the complex ion hexaquatitanium (III) ion.

(a) Write the formula of the complex ion. (1 mark)

(b) Specify the two types of bonding present in this ion. (1 mark)

(c) Explain why methane cannot form a similar complex with Ti2+. (1 mark)

QUESTION 5

(a) Copper II sulphide dissolves according to the following equation:

CuS(s) Cu2+(aq) + S2-(aq)

Explain why the following expression for the solubility product of copper II sulphide is not correct: Ksp = [Cu2+(aq)] [S2–(aq)]

(1 mark)

(b) Describe a trend in the properties, down the group from carbon to lead, of the

(i) oxides of CO2, SiO2, SnO2, PbO2

(ii) chlorides of CC14, SiCl4, SnCl4, PbCl4

(1 mark)

(c) Calculate the oxidation number of chromium in CrO2Cl2. (1 mark)

Turn Over

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11.

SECTION B (continued)

QUESTION 6

(a) Consider the reaction given below.

+ Br2

Use the enthalpy data given below to calculate the heat of reaction.

Bond Bond Energy

(kJmol -1)

C – C 348

C = C 614

C – Br 218

C – H 413

Br – Br 192

(2 marks)

(b) Explain whether the reaction above is exothermic or endothermic. (1 mark)

QUESTION 7

There are four structural isomers with the formula C4H9C1, one of which exists in

optically active form.

(a) Draw the structure that exists as an optical isomer of C4H9C1. (1 mark)

(b) Draw two other isomers of C4H9C1. (2 marks)

QUESTION 8

Draw the structural formula of the major product of the following reactions.

(a) C3H8 + Br2 UV (1 mark)

(b) C3H7OH + PC15 (1 mark)

O ║

(c) CH3CH2CC1 + CH3NH2 (1 mark)

CH2

CH2 CH2

CH CH

CH2 CH2

H-C-Br

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QUESTION 9

(a) Explain the term functional group using CH3COCH3 as an example. (1 mark)

(b) Terylene is a polyester produced from the two monomer units given below.

(i) Define the term polyester. (1 mark)

(ii) Draw the structural formula for a segment of the polyester made from the

two monomers given above. (1 mark)

QUESTION 10

Show by means of calculations that a precipitate forms when 50.0 ml of 0.10 molL-1 KCl solution and 50.0 ml of 0.02 molL-1 AgNO3 solution are mixed.

[Ksp (AgCl) = 1.56 x 10

–10

]

(3 marks) QUESTION 11

(a) Balance the oxidation half equation given below.

Mn(OH)2 MnO4 2– (1 mark)

(b) Balance the reduction half equation given below.

SO2Cl2 SO32– + Cl– (1 mark)

(c) Combine the balanced half equations in (a) and (b) above to write the

overall ionic redox equation in basic medium. (1 mark)

QUESTION 12

Use the information given below to answer the questions that follow.

The half–cell reactions and their standard reduction potentials for a galvanic cell are shown below.

AgCl(aq) + e –

Ag(s) + Cl –

(aq) Eº = + 0.22 V

Ni2+(aq) + 2e– Ni(s) Eº = – 0.26 V

(a) What does the term standard reduction potential mean? (1 mark)

(b) Write the equation for the spontaneous cell reaction. (1 mark)

(c) Calculate Eºcell for the cell reaction. (1 mark)

Turn Over

O O

C

HO _C OH HO C C OH

H

H H

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13.

SECTION

C

[40 marks]

The five questions in this section are all compulsory. Each question is worth 8 marks.

QUESTION 1

(a) (i) Complete the orbital diagram for Fe and Fe3+ given in your Answer Book. (1 mark)

(ii) Suggest why Fe3+ is a more stable ion than Fe2+ under normal

conditions. (1 mark)

(b) Naturally occurring bromine is composed of two isotopes, 79Br and 81Br.

Use this information and the relative atomic mass of bromine of 79.90 to

calculate the relative abundances of these two isotopes. Show all working. (2 marks)

(c) A student allowed a sample of a gas to flow into a 300 ml gas bulb until the pressure was 91.30 kPa. The temperature was kept at 26ºC and the sample now weighed 1.45 g.

Calculate the molar mass of the gas. Show all working and give the final answer

as a whole number. [R = 8.314 Jmol–1K–1] (2 marks)

(d) Choose an element from sodium to chlorine in Period 3 that will react with oxygen to give a basic oxide and write chemical equations to show:

(i) its reaction with oxygen to form the oxide. (1 mark)

(ii) the reaction of the oxide formed in part (i) above with water to illustrate the

basic nature of the oxide. (1 mark)

QUESTION 2

(a) (i) Draw the Lewis structure of the SO4

2–

ion. (1 mark)

(ii) Name the shape of the ion and give a reason for your answer. (1½ marks)

(b) Complete the table in your Answer Book by writing the balanced equation for the reaction of phosphorous pentachloride (PCl5) with water. Suggest the

approximate pH of the solution formed by adding about 1 g of phosphorous pentachloride to 100 cm3 of water. [No calculations are necessary.]

(1½ marks)

Equation pH

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(c) Explain briefly why zinc may be regarded as a d-block element but not a transition

metal. (1 mark)

(d) A gas of molar mass 30 g/mol contained in a container of fixed volume of 1 dm3 at a temperature of 300 K exerts a pressure of 1 atmosphere on its wall area of 100 cm2.

What will the new pressure be, if the:

(i) temperature of the gas is raised to 327 K?

[Show all necessary workings.] (1 mark)

(ii) gas is replaced by an equal number of molecules with molar

mass of 45 g/mol? Justify your answer. (2 marks)

QUESTION 3

(a) Use the data below to explain concisely why zinc is used in preference to tin for coating steel which is used in cars.

Eº/V

Sn2+(aq) + 2e– Sn(s) –0.14

Fe2+(aq) + 2e– Fe(s) –0.44

Zn2+(aq) + 2e– Zn(s) –0.76

(2 marks)

(b) Classify the solids Y and Z as metallic, non-metallic, ionic or macromolecular according to the properties given in the table below.

(1 mark)

Turn Over

Solid Properties

Y

The solid is soft and has a low melting point. The solid is a non-conductor of electricity in its molten and aqueous states.

Z

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15.

SECTION C (continued)

(c) Iron (III) oxide can be reduced to iron using hydrogen.

Fe2O3(s) + 3H2(g) 2Fe(s) + 3H2O(g)

(i) Calculate the enthalpy change for the reaction using the following enthalpy of formation values.

Substance ΔΗof (kJmol–1)

Fe2O3(s) –822

H2(g) 0

Fe(s) 0

H2O(g) –242

(2 marks)

(ii) ΔΗof refers to the standard enthalpy of formation.

Define the term standard enthalpy of formation. (1 mark)

(d) In human beings, one buffer system in blood involves the hydrogen carbonate ion, HCO3– and carbonic acid, H2CO3 which is formed when carbon dioxide dissolves

in water.

Explain using an equation how this buffer maintains a constant pH of

7.41 even if a small amount of acid enters the bloodstream. (2 marks)

QUESTION 4

(a) Give the systematic name of the organic compounds given below.

(i) (ii)

(2 marks)

CH3 H

H H

C C C N CH3

H H CH3

H

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(b) Nicotinic acid is used in the treatment of high cholesterol levels. The molecular formula for nicotinic acid is C5H4NCOOH.

(i) Write an equation to show the dissociation of nicotinic acid in water. (1 mark)

(ii) Write an expression for the dissociation constant, Ka of nicotinic acid. (1 mark)

(iii) The Ka value of nicotinic acid is 1.4 x 10–5.

Calculate the concentration of a nicotinic acid solution which has a

pH of 3.77. Assume that the concentration of nicotinic acid is not affected by

the dissociation. (2 marks)

(c) A solution of ammonium chloride contains the following species:

H2O H3O Cl– NH3 NH4

The concentrations of these species are presented on the bar graph given below.

A B C D E

Identify the four species labelled B, C, D and E. (2 marks)

Turn Over

species

C

onc

entra

ti

on mol

L

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17.

QUESTION 5

Consider the following reaction sequence to answer the questions that follow.

I

X

Y

K2Cr2O7/ H+

+

NH2OH

(a) Name the compounds B, D, F and G. (2 marks)

(b) Identify the following reaction conditions labelled I and II. (1 mark)

(c) Name the reagents labelled X and Y. (1 mark)

(d) Identify the types of reaction for the formation of the following compounds:

(i) A (ii) D (iii) F

(iv) G (2 marks)

(e) Write chemical equations using structural formula for the formation of the

compounds A and F. (2 marks)

THE END

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COPYRIGHT: MINISTRY OF EDUCATION, REPUBLIC OF FIJI, 2012.

Compound A C3 H6

Compound B C3 H7 Br

Compound C C3 H8 O

Compound D C3 H6 O

Compound E C3 H6 O2

Compound C C3 H8 O

Compound F Compound G