SSC FSFE Chen 2010 QP.pdf

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MINISTRY OF EDUCATION

FIJI SEVENTH FORM CERTIFICATE EXAMINATION 2010

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.

36 65 minutes

C There are five questions.

40 72 minutes

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2.

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. The correct electron configuration characteristic of a Group II element is A. 1s2 2s2 2p6 3s2 3p2

B. 1s2 2s2 2p6 3s2 3p6 4s2 C. 1s2 2s2 2p6 3s2 3p6 3d2 D. 1s2 2s2 2p6 3s2 3p6 3d6 4s2

2. Which of the following sets of quantum numbers is correct? A. n = 0, l = 0, ml = 0

B. n = 2, l = 2, ml = 1 C. n = 2, l = 1, ml = 0 D. n = 2, l = 1, ml= -2

3. Consider the following molecules: HCl H2S RbCl BrCl

The molecule with the largest dipole moment is

A. H2S B. HCl C. BrCl D. RbCl

© MINISTRY OF EDUCATION, FSFCE 2010: CHEMISTRY.

12 A B C D

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3.

4. Refer to the following ions:

O2- F– Na+ Mg2+

Considering their electron configuration, which of the following statements given below is correct?

A. O2- and F– have the same configuration. B. All four ions have the Neon configuration. C. None of the ions has the Neon configuration. D. Only Na+ and Mg2+ have the same configuration.

5. The data in the following table was obtained by changing the pressure on 100 cm3 of nitrogen. Temperature was constant throughout.

Pressure (P) Volume (V) PV

100 kPa 100 cm3 10,000 kPa cm3

200 kPa 50 cm3 10,000 kPa cm3

400 kPa 25 cm3 10,000 kPa cm3

Which of the following gas laws does the above data verify?

A. Boyle’s Law B. Charle’s Law C. Gay – Lussac’s Law

D. Dalton’s Law of Partial Pressure

6. Some hydrogen gas is collected over water at 25°C and 102.8 kPa. The uncorrected volume is found to be 60 ml. Water vapour pressure at 25°C is 3.2 kPa. The volume of dry

hydrogen gas at STP would be

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4.

7. The equation for the burning of carbon monoxide is

2CO(g) + O2(g) 2CO2(g) H = -566 kJ [Ar : C = 12, O = 16]

When 14 g of carbon monoxide is burnt, the enthalpy change, H is

A. - 141.5 kJ B. - 70.8 kJ C. + 566.0 kJ D. + 1132.0 kJ

8. The standard heat of formation of sulphuric acid is the heat change associated with the reaction:

A. H2(g) + S(s) + 2O2(g) H2SO4(l) B. 2H(g) + SO2(g) + 2O(g) H2SO4(l) C. 2H(g) + S(s) + 4O(g) H2SO4(l) D. H2O(l) + SO3(g) H2SO4(l)

9. The element that forms the most acidic oxide is A. sodium.

B. phosphorus. C. magnesium. D. aluminium.

10. The oxidation state of Pt in the complex [Pt (NH3)4Cl2]2+ is A. - 4

B. + 2 C. + 3 D. + 4

11. As the atomic number of elements in Group IV increases, the A. oxide XO becomes more acidic.

B. hydride XH4 becomes more stable. C. chloride XCl2 becomes more ionic. D. + 4 oxidation state becomes more stable.

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5.

12. The solution of the compound which is the most basic is

A. CH3CH2NH2 B. (CH3)2NH C. (CH3)3N D. NH3

13. The formation of the compound given below is best described as

A. oxidation. B. esterification. C. saponification. D. transesterification.

14. Which one of the following molecules has an optical isomer?

A. CH3CH(COOH)CH2CH3 B. CH3CH2C(CH3)2OH C. H3CCH2Cl

D. CH3CHCl2

15. The reaction of CH3CH2COCl and CH3OH would produce

A. butan-2-one. B. propyl acetate. C. methyl butyrate. D. methyl propanoate.

16. The two formulae, C4H8 and C7H14 represent two

A. alkanes.

B. members of a homologous series. C. isomers of the same hydrocarbon.

D. possible empirical formulae for the same compound.

Turn Over © MINISTRY OF EDUCATION, FSFCE 2010: CHEMISTRY.

CH2OOC(CH2)16CH3

CHOOC(CH2)16CH3

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6.

17. The structural formula of trans-but-2-en-l-ol is

A. CH3 H B. CH3 H

C = C C = C

OHCH2 H H CH2OH

C. CH3 OH D. CH3 CH2OH

C = C C = C

CH3 H H H

18. The systematic name of the compound given below is

A. 2-chloro-2, 4-dimethylbutanone. B. 4-chloro-2, 4-dimethylbutanone. C. 2-chloro-2-methylpentan-2-one. D. 4-chloro-4-methylpentan-2-one.

19. Which one of the following is the weakest acid?

Acid Ka pKa

A. citric acid 7.1 x 10-4 3.15

B. phosphoric acid 7.1 x 10-3 2.15 C. carbonic acid 4.5 x 10-7 6.35 D. sulphuric acid 1.2 x 10-2 1.92

20. When 10 ml of a 0.1 mol L-1 solution of hydrochloric acid is diluted to 1 litre, the pH of the resulting solution is

A. 10-3 B. 1 C. 3 D. 103

© MINISTRY OF EDUCATION, FSFCE 2010: CHEMISTRY. Cl

C

CH3

CH2 C CH3 CH3

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7.

21. The equilibrium equation and the Ka expression of 1.0 mol L-1 solution of oxalic acid are as follows: ) aq ( 4 2 ) aq ( ) aq ( 4 2

2C O H HC O

H K 298 at 10 x 6.4 ] O C [H ] O [HC ] [H K 5 4 2 2 4 2 a

Which of the following species will be present in the greatest concentration at equilibrium?

A. H (aq)

B. H₂C₂O₄₍_aq₎

C. HC₂O₄₍_aq₎

D. H (aq) and HC₂O₄₍_aq₎

22. Which one of the following compounds is the strongest bronsted base?

A. HCO₃₍_aq₎

B. HSO₄₍_aq₎

C. CH₃COO (aq)

D. NO₃₍_aq₎

23. The [H3O+] of a 0.10 mol L-1 solution of NH4Cl in water at 25°C is

A. 5.6 x 10-10 B. 1.8 x 10-6 C. 7.5 x 10-6 D. 1.8 x 10-5

[Kb (NH3) = 1.8 x 10-5]

24. In the reaction Ni₍2_aq₎ Fe₍2_aq₎ Ni₍_s₎ Fe3₍_aq₎ the reducing agent is

A. Ni(s) B. Ni2+(aq) C. Fe2+(aq) D. Fe3+(aq)

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8.

SECTION B

[36 marks]

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

QUESTION 1

Antimony (Sb) contains 121₅₁ Sb and 123₅₁Sb. If its relative atomic mass is 121.8,

determine the percentage abundance of each isotope. (3 marks)

QUESTION 2

(a) Draw the Lewis structure of Cl2O and predict its shape. (1 mark) (b) Account for the fact that PCl3 is pyramidal but BCl3 is planar in shape. (1 mark) (c) Write down the four quantum numbers for one of the electrons in the s orbital of

the third energy level of the phosphorus atom. (1 mark)

QUESTION 3

Potassium chlorate (KClO3) is decomposed by heating in an experiment. It gives a certain amount of potassium chloride (KCl) and 638 cm3 of oxygen (O2) gas at a temperature of 18°C and a pressure of 0.989 KPa. The equation for the reaction is given below:

2 KClO3(s) 2 KCl(s) + 3 O2(g)

[M (KCl) = 74.5 gmol-1; R = 8.314 J mol-1K-1]

(a) Calculate the amount (in moles) of O2 gas produced. (2 marks)

(b) Calculate the mass of KCl produced. (1 mark)

QUESTION 4

(a) Below is an outline of the Periodic Table with a number of elements included. Use only the elements in this table to answer the questions that follow. Each element is to be used only once.

Write the symbol of the element which:

(i) has the highest electronegativity. (½ mark)

© MINISTRY OF EDUCATION, FSFCE 2010: CHEMISTRY. H

K Ca V Fe Cu Zn

I Al Si P S

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9.

(ii) has an oxide that is insoluble in water and reacts with both base

and acid. (½ mark)

(iii) forms a hydride with a trigonal pyramid shape. (½ mark)

(iv) is metallic and has oxidation states of +1 and +2. (½ mark)

(b) What is the function of a buffer solution? (1 mark)

QUESTION 5

Consider the complex ion [Cr (NH3)6]3+

(a) Name the complex ion. (1 mark)

(b) Explain the term ligand with reference to the above complex ion. (1 mark)

(c) What is the coordination number of the complex ion? (½ mark)

(d) State one characteristic property of this complex ion. (½ mark)

QUESTION 6

(a) (i) Calculate the heat of reaction for the following reaction using the bond energy data given below.

Bond Bond Energies

(kJ mol-1)

H – H 436

C – H 413

C – C 348

C = C 614

(2 marks)

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

H

C = C CH3

CH3

+ H2

H

C

H

H C CH3

CH3

H

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10.

SECTION B (continued)

QUESTION 7

(a) Draw the structural formula of 2, 3-dihydroxybut-2-ene. (1 mark)

(b) From the List of Compounds given below, select the letter of one which is

(i) an ester. (½ mark)

(ii) a secondary alcohol. (½ mark)

(iii) a ketone. (½ mark)

(iv) an alkyne. (½ mark)

List of Compounds

A. (CH3)3COH D. CH3CH2COOCH3

B. CH3CH2OCH3 E. CH3CH2COCH3

C. CH3CH2CCCH3 F. CH3CH2CH(OH)CH3

QUESTION 8

Give the structural formula of the major organic product of the following transformations.

(a) CH2 = CH – C = CH – CH3 (1 mark)

CH3

(b) CH3COCl + NH3 (1 mark)

(c) (CH3)2CHCOOH + SOCl2 (1 mark)

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11.

QUESTION 9

(a) Determine the reaction type in each of the following reactions:

(i) CH3 CH2 CH2 Br CH3 CH CH2 + HBr (½ mark)

(ii) + H2 (½ mark)

(iii) CH3 CH2 CH2 I + NaOH CH3CH2CH2 OH + NaI (½ mark)

(b) Vitamin C has the structure:

(i) Circle the section that would readily react to decolourise bromine water. (½ mark)

(ii) Classify A and B as primary, secondary or tertiary alcohol groups. (1 mark)

QUESTION 10

An environmental chemist needs a carbonated buffer of pH 10 to study the effects of soil acidification. What mass of sodium carbonate must be added to 1.5 L of 0.20 mol L-1 NaHCO3 to make the buffer?

] 10 x 7 . 4 ) HCO ( K ; gmol 106 ) CO Na ( M

[ ₂ ₃ 1 _a ₃ 11

(3 marks)

OH

H2C

CH

HC

O

C

HO

C

C O

OH OH

A

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12.

SECTION B (continued)

QUESTION 11

(a) A solution is made by mixing 500 ml of 0.50 molL 1 C2H5NH2 (ethylamine) with 500 ml of 0.20 molL 1

HCl. The pH of the resulting solution is found to be 10.93. Calculate the concentration of OH₍_aq₎ in the solution.

[Assume that the volumes are additive.] (2 marks)

(b) (i) Define the term strong electrolyte. (½ mark)

(ii) Give an example of a strong electrolyte. (½ mark)

QUESTION 12

The following questions are based on the unbalanced equation:

) g ( )

aq ( 4 3 )

aq ( 3 )

s ( 3

2O NO H AsO NO

As

(a) Write the balanced oxidation half equation. (1 mark)

(b) Write the balanced reduction half equation. (1 mark)

(c) Use the half equations in (a) and (b) above to write the overall balanced equation

in a basic medium. (1 mark)

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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) Two sets of four quantum numbers for an element Z are given below. Study the two sets and answer the questions that follow:

Set A Set B

n l ml ms n l ml ms

1 0 0 + ½ 1 0 0 + ½

1 0 0 – ½ 1 0 0 + ½

2 0 0 + ½ 2 0 0 + ½

2 0 0 – ½ 2 0 0 – ½

2 1 – 1 + ½ 2 1 – 1 + ½

(i) How many electrons does element Z have? (½ mark)

(ii) Which set of quantum numbers is the correct set for the element Z? (½ mark)

(iii) Give a reason for your answer to (ii) above. (1 mark)

(iv) Why does element Z have a much lower first ionization energy than

helium? (1 mark)

(b) Write the electron configuration for Chromium using s, p, d notation. (1 mark)

(c) Hydrogen peroxide, H2O2 (M = 34 gmol-1) is a powerful oxidising agent that is used in concentrated solution in rocket fuel systems and in dilute solution as in hair bleach. An aqueous solution of H2O2 is 30% by mass and has a density of 1.11 g/cm3.

Express the concentration of the solution in terms of:

(i) molality (1 mark)

(ii) mole fraction of H2O2 (1 mark)

(iii) molarity (2 marks)

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14.

SECTION C (continued)

QUESTION 2

(a) The following are the oxides of some of the elements of period 2:

LiO2 BeO B2O3 CO2 N2O

(i) What is the natural state of:

I. LiO2?

II. CO2? (1 mark)

(ii) Write equations for the reactions of water with:

I. LiO2

II. CO2 (1 mark)

(iii) What would be the nature (acidic, basic or neutral) of the aqueous

solutions of the oxides mentioned in part (ii) above? (1 mark)

(b) Account for the following:

(i) The radius of the aluminium ion is much smaller than the radius of the

aluminium atom. (1 mark)

(ii) The melting point of silicon dioxide is much higher than that of sulphur

dioxide. (1 mark)

(c) Consider the following enthalpy data:

H°c (H2(g)) = - 282 kJ mol-1

H°f (H2O(l)) = - 282 kJ mol-1

(i) Explain fully what is meant by:

H°c (H2(g)) = - 282 kJ mol-1 (1 mark)

(ii) Account for the fact that the two values of H°f (H2O(l)) and H°c (H2(g))

are equal. (1 mark)

(iii) What are the standard conditions for thermochemical measurements? (1 mark)

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15.

QUESTION 3

(a) The following diagram represents the titration curve for the reaction of an aqueous solution of methanamine (CH3 NH2) with hydrochloric acid.

(i) Is methanamine a strong base or a weak base? (½ mark)

(ii) Which letter on the curve represents the equivalence point of the

reaction? (½ mark)

(iii) Between which two letters does the curve represent the region in which

buffering action is observed? (½ mark)

(iv) Which letter represents the point where [CH3NH2] = [CH3NH3+]? (½ mark)

(v) Estimate the value of pKa of CH3NH3+. (½ mark)

10 20 30

0 2 4 6 8 10 12

Volume of hydrochloric acid (mL) pH

A B

C

D

E

F

G

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16.

(b) A solution of calcium chloride contains the following species.

Ca2+, H2O, OH-, Cl-, H3O+

The concentration of these species are represented on the bar graph given below.

Identify the five species labelled M, N, O, P, Q. (2½ marks)

(c) Using the standard reduction potentials given below, calculate the E°cell for the following reaction:

2 Ag+(aq) + 2 I–(aq) 2 Ag(s) + I2(g)

E° : Ag+ / Ag = + 0.80 V

I2 / I– = + 0.53 V (1 mark)

(d) Study the following galvanic cell.

mol L-1

M N O P Q

species

v

Al Sn

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17.

(i) In which direction will electrons flow? (½ mark)

(ii) In which half cell will electrons enter the cell? (½ mark)

(iii) At which electrode are electrons consumed? (½ mark)

(iv) In which direction do cations within the salt bridge move to maintain

charge neutrality? (½ mark)

QUESTION 4

(a) Indicate the chemical(s) required and any special condition(s) needed to bring about the following conversions:

(i) ethene to ethane. (1 mark)

(ii) 2-bromobutane to 2-butanol. (1 mark)

(iii) 2-butanol to butanone. (1 mark)

(b) Write the systematic name of the compound with the formula C(CH3)4. (1 mark)

(c) Comment on the following:

(i) Applying a volatile liquid such as methylated spirit on to the skin before

an injection makes the skin feels cool. (1 mark)

(ii) Bromine has a higher melting point than chlorine in spite of the fact that

it has a lower bond enthalpy than chlorine. (1 mark)

(d) The solubility of BaF2 in water is 7.5 x 10-3 mol L-1. Calculate the Ksp of

BaF2. (2 marks)

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18.

QUESTION 5

(a) Consider the following reaction sequence to answer the questions that follow.

(i) Name the compounds A, B, C, D, E and F. (3 marks)

(ii) Name the Reagents M and N. (1 mark)

(iii) Write the equations for Reaction I and Reaction II. (2 marks)

(b) Benzene and propene are unsaturated compounds.

(i) In what general way do the reactions of benzene and propene differ? (1 mark)

(ii) Write an equation to show the reaction of benzene with chlorine. (1 mark)

THE END

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COPYRIGHT: MINISTRY OF EDUCATION, REPUBLIC OF THE FIJI ISLANDS, 2010. CH2 = CH – CH3

propene Compound A

Compound B

CH3(CH2)2NH2

Compound C

CH3CH(OH)CH3

Compound D

C3H8O

Compound E

C3H6O2

Compound F

O CH3CH2 C

ONa

HCl Reaction I

NH3

H2O/H+

Reagent M

Reagent N