2012

HSC TRIAL EXAMINATION PAPER

Chemistry

General Instructions

Reading Time – 5 minutes

Working Time – 3 hours

Write using black or blue pen

Draw diagrams using pencil

Board-approved calculators

may be used

A data sheet and Periodic

Table are provided at the back

of this paper

Write your Student Number at

the bottom of this page and on

page 7

Total Marks - 100

Section I Pages 2–15

75 marks

This section has two parts, Part A and Part B

Part A – 20 marks

Attempt Questions 1–20

Allow about 35 minutes for this part

Part B – 55 marks

Attempt Questions 21–31

Allow about 1 hour and 40 minutes for this part

Section II Pages 16–23

25 marks

Attempt ONE question from Questions 32–36

Allow about 45 minutes for this section

Student Name: __________________________________

Chemistry HSC Trial 2012

– 2 –

Section I

75 marks

Part A – 20 marks

Attempt Questions 1–20

Allow about 35 minutes for this part

Use the multiple-choice answer sheet for Questions 1-20

1 Decane is cracked to produce an alkane and ethylene.

Which equation correctly shows this reaction?

(A) C10H22(l) → C8H18(l) + C2H4(g)

(B) C10H20(l) → C8H18(l) + C2H2(g)

(C) C12H24(l) → C10H18(l) + C2H4(g)

(D) C12H26(l) → C9H18(l) + C3H8(l)

2 Which of these molecules is a monomer used in the production of an addition polymer?

(A) CH4

(B) C2H6

(C) C2H3Cl

(D) C3H7Cl

3 Which substance is used as a catalyst in the initial stage of polymerisation of

polyethylene?

(A) Zeolite crystals

(B) Organic peroxides

(C) Fine iron oxide powder

(D) Platinum

4 Which equation represents a renewable source of ethanol?

(A) C2H4(g) + H2O → C2H5OH(l)

(B) C2H5OH(l) → H2O + C2H4(g)

(C) C6H12O6 + C6H12O6 → C12H22O11 + H2O

(D) C6H12O6(aq) → 2C2H5OH(l) + 2CO2(g)

Chemistry HSC Trial 2012

– 3 –

5 Use the information in the following table to answer the question.

Name of fuel Formula Molar Heat of Combustion

(kJ mol-1

)

Hydrogen H2 -286

Ethanol C2H5OH -1367

Butanol C4H9OH -2677

Octane C8H18 -5464

Which fuel releases the most energy per gram?

(A) Hydrogen

(B) Ethanol

(C) Butanol

(D) Octane

6 Which list contains only substances which will oxidise copper metal to Cu2+

`?

(A) Fe2+

(aq) ,Ca2+

(aq) , Zn2+

(aq)

(B) Br2 (aq) ,Cl-1

(aq), Pb+2

(aq)

(C) F-1

(aq) , Cl-1

(aq), Br-1

(aq)

(D) Ag+1

(aq), Cl2(g) , Br2(l)

7 Which statement is correct?

(A) The dry cell (Leclanchẻ cell) is rechargeable.

(B) The electrode reactions in a lead acid battery are reversible.

(C) The dry cell contains sulphuric acid which is hazardous.

(D) The lead acid battery is less toxic to the environment than a dry cell.

8 Why does a radioisotope such as Carbon-14 decay to release beta particles?

(A) Too many neutrons for the number of protons

(B) Too many protons for the number of neutrons

(C) Too many protons and neutrons in the nucleus

(D) Too much energy in the nucleus

Chemistry HSC Trial 2012

– 4 –

9 Which list correctly shows an acidic oxide, an amphoteric oxide and a basic oxide?

(A) SO2, SnO2, CaO

(B) SO2, Cl2O7, CO2

(C) MgO, BaO, K2O

(D) Na2O, Al2O3, K2O

10 Copper sulfide reacts with oxygen to form sulfur dioxide according to the following

equation:

2CuS(s) + 3O2(g) ↔ 2CuO(s) + 2SO2(g)

What volume of oxygen gas at 00C and 100kPa is required to produce 128.2 grams of

SO2?

(A) 14.99 litres

(B) 22.71 litres

(C) 45.42 litres

(D) 68.13 litres

11 The following reaction is at equilibrium in a sealed flask:

2NO2(g) ↔ N2O4(s) ∆H = - 60kJ mol-1

The reaction temperature is then increased.

What will happen to the pressure inside the flask?

(A) It will stay the same

(B) It will increase

(C) It will decrease

(D) It will increase then decrease as a new equilibrium position is reached

12 10 mL of a hydrochloric acid solution with a pH of 2, is diluted to 1000 mL.

What is the pH of the diluted solution?

(A) 0.02

(B) 2

(C) 4

(D) 6

Chemistry HSC Trial 2012

– 5 –

13 25 mL of 0.02 M potassium hydroxide solution in a conical flask is neutralized by the

gradual addition of 25 ml of 0.02 M nitric acid.

What happens to the hydrogen ion concentration of the solution in the flask?

(A) [H+] remains constant as the acid is added

(B) [H+] starts at zero then increases

(C) [H+] starts at zero then decreases

(D) [H+] is very small at the start then increases

14 Which salt solution would have a pH less than 7?

(A) NH4Cl,

(B) NaCl,

(C) KCH3COO

(D) NaCH3COO

15 How many isomers are there for C2H2Br2Cl2?

(A) Two

(B) Three

(C) Four

(D) Five

16 Which method of analysis is most suitable to determine the concentration of mercury

present in shark meat?

(A) AAS

(B) Flame test

(C) Gravimetric analysis

(D) Volumetric analysis

17 Which compound would have the least capacity to damage the ozone layer?

(A) 1,1,1-trichloroethane

(B) 1,1,1,2-tetrafluoroethane

(C) Chlorodifluoromethane

(D) Bromomethane

Chemistry HSC Trial 2012

– 6 –

18 Water samples from four locations along a river are tested and are compared with

recommended values for clean water. The results are recorded in the following table.

Test Recommended

valves for

clean water

Location

W

Location

X

Location

Y

Location

Z

Biological Oxygen

Demand (mgL-1

)

<5 5 15 2 1

Dissolved Oxygen

(mgL-1

)

7-9 7 9 6 10

Total phosphate

(mgL-1

)

<0.03 0.01 0.1 0.05 0.003

Total dissolved

solids (ppm)

<100 300 95 150 98

Which location is most at risk of eutrophication?

(A) W

(B) X

(C) Y

(D) Z

19 Which cation can be identified using sodium chloride solution?

(A) Fe+3

(B) Ag+

(C) Cu+2

(D) SO4-2

20 Which contaminant would most likely pass through a membrane filter with a pore

diameter of 0.2 micrometres?

(A) Calcium ions

(B) Pesticide molecules

(C) Clay particles

(D) Microorganisms

Chemistry HSC Trial 2012

– 7 –

2012 TRIAL HIGHER SCHOOL CERTIFICATE EXAMINATION

Chemistry Student Name: ____________________

Section I — (continued)

Part B – 55 marks

Attempt Questions 21–31

Allow about 1hour 40 minutes for this part

Answer the questions in the spaces provided. These spaces provide guidance for the expected length of

response.

Show all relevant working in questions involving calculations.

Question 21 (4 marks)

(a) Define the term condensation polymer and give an example.

2

(b) Identify the monomer present in your named condensation polymer and draw its

structural formula.

2

Chemistry HSC Trial 2012

– 8 –

Question 22 (6 marks)

Ethanol can be both a renewable and a non-renewable resource.

Justify this statement using chemical equations to support your answer.

6

Chemistry HSC Trial 2012

– 9 –

Question 23 (3 marks)

Two students were measuring the potential difference (voltage) generated in a galvanic

cell.

They used a nickel electrode in a beaker containing nickel nitrate solution. A zinc

electrode in a beaker of zinc nitrate made up the other half cell. The electrodes were

connected to a voltmeter using leads. The beakers were connected using a salt bridge.

(a) Write the overall equation for the galvanic cell reaction.

1

(b) Calculate the cell voltage under standard conditions. Show working out.

2

Question 24 (4 marks)

Explain the formation and effects of acid rain

4

Chemistry HSC Trial 2012

– 10 –

Question 25 (4 marks)

The flow diagram shows a series of tests that can be used to identify carbonate, chloride and sulfate

ions present in a sample.

(a) Identify the gas observed during Step 1.

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

(b) Explain why the analysis must be performed in the sequence given.

1

3

Chemistry HSC Trial 2012

– 11 –

Question 26 (6 marks)

25 mL of a 0.20 mol L-1

standardised sodium hydroxide solution was titrated with a

sulfuric acid solution. The results are recorded in the table below.

Titration Volume of sulfuric acid used

(mL)

rough 32.8

1 29.1

2 28.9

3 29.0

(a) Write the balanced equation for this reaction.

1

(b) Calculate the concentration of sulfuric acid, in mol L-1

.

3

(c) Explain how the sodium hydroxide solution could have been standardised.

2

Chemistry HSC Trial 2012

– 12 –

Question 27 (7 marks)

You performed a first-hand investigation to prepare an ester by reflux in the presence of

concentrated sulfuric acid.

(a) Identify the products formed when methanoic acid and butanoic acid are refluxed.

1

(b) Justify the use of refluxing and concentrated sulfuric acid in the preparation of an

ester.

4

(c) Identify TWO hazards associated with this first-hand investigation and describe the

safety precautions which can minimise the risk of injury.

2

Chemistry HSC Trial 2012

– 13 –

Question 28 (4 marks)

Explain how a buffer works with reference to a specific example in a natural system.

Question 29 (5 marks)

Evaluate the significance of the development of the Haber process on early twentieth

century world history.

5

4

Chemistry HSC Trial 2012

– 14 –

Question 30 (5 marks)

The diagram represents a section of the layered structure of Earth’s atmosphere.

(a) Identify the layers of atmosphere labelled X and Y.

X .............................................................................

Y .............................................................................

(b) Ozone is a gas found in layers X and Y. Explain the effect of ozone in each of these layers.

1

4

Chemistry HSC Trial 2012

– 15 –

Question 31 (7 marks)

An analytical chemist determined the phosphate concentration of water samples from three

local streams.

(a) Using the absorbance values in the table and graph, determine the mean absorbance and

mean phosphate concentration for each stream and complete the table.

(b) The recommended maximum level of phosphate in streams is 0.100 mg L–1 .

With reference to the recommended maximum level of phosphate for stream

water, explain why there are differences between the three streams.

2

3

Chemistry HSC Trial 2012

– 16 –

(b) Describe TWO factors that affect hardness of a natural body of water.

2

End of Section I

Chemistry HSC Trial 2012

– 17 –

2012 TRIAL HIGHER SCHOOL CERTIFICATE EXAMINATION

Chemistry

Section II

25 marks

Attempt ONE question from Questions 32–36

Allow about 45 minutes for this section

Answer the parts of the question in a writing booklet. Clearly label each part of the question.

Show all relevant working in questions involving calculations.

Pages

Question 32

Industrial Chemistry 17

Question 33

Shipwrecks, Corrosion and Conservation 18

Question 34

The Biochemistry of Movement 19

Question 35

The Chemistry of Art 20

Question 36

Forensic Chemistry 21

Chemistry HSC Trial 2012

– 18 –

Question 32 — Industrial Chemistry (25 marks)

(a)

Carbon monoxide reacts with chlorine to produce carbon oxychloride as shown by the following

equation.

CO(g) + Cl2(g) ↔ COCl2(g) ∆H = -5kJ mol-1

A 10 litre reaction vessel initially contained 2.0 moles carbon monoxide and 5.0 moles

chlorine gas at 2000C. When the reaction reached equilibrium, there was 1.0 mole of carbon

monoxide remaining.

(i) Calculate the equilibrium concentration of carbon monoxide, chlorine and

carbon oxychloride.

3

(ii) Write the equilibrium expression for this reaction then calculate the value for

K. Show relevant working.

2

(iii) Predict the effect on the reaction direction by lowering the temperature. Explain

your answer using Le Chatelier’s Principle.

1

(iv) What effect would lowering the temperature have on the equilibrium constant?

1

(b) During your course you performed a first-hand investigation to identify the products of the

electrolysis of aqueous sodium chloride.

(i) Outline the procedure you used to electrolyse the aqueous sodium

chloride.

2

(ii) Describe your observations at the anode and the cathode and write a half

equation for each reaction.

3

(iii) Explain how the products of electrolysis vary with the concentration of the

solution.

2

(c) The table shows the structures of three different classes of detergents.

(i) Account for the cleaning action of anionic detergents.

(ii) Assess the environmental impacts of the different classes of detergents.

2

4

Chemistry HSC Trial 2012

– 19 –

(d) Sulfuric acid is one of the world’s most significant industrial chemicals because of the

variety and importance of its uses.

(i) Outline the industrial process for the manufacture of sulfuric acid from its

raw materials.

(ii) Account for the safety precautions associated with the industrial transport

of sulfuric acid.

3

2

Chemistry HSC Trial 2012

– 20 –

Question 33 — Shipwrecks, Corrosion and Conservation (25 marks)

(a) Initial explanations of phenomena are often replaced as technological

developments change scientific thinking.

Assess the work of FOUR early scientists in increasing our understanding of

electron transfer reactions.

5

(b) An electrolytic cell consisting of a solution of 0.1 M sodium nitrate and two

graphite electrodes is set up in a beaker.

(i) Write the half equations for the reactions taking place at the anode and

cathode.

2

(ii) What minimum voltage would be required to operate this electrolytic cell?

1

(iii) Outline TWO methods of increasing the rate of electrolysis of this cell.

2

(c) A manufacturer of rotary steel clothes lines was investigating various methods of

protecting the clothes lines against corrosion.

(i) Explain THREE methods of protecting steel against corrosion.

3

(ii) Make a recommendation as to the most suitable method of corrosion

protection for the clothesline manufacturer and justify your selection.

2

(d) The wreck of the Titanic has lain on the ocean floor for 100 years in very deep,

cold water.

Assess the significance of the Titanic (or other wrecks at great depths) in terms

of modifying our understanding of the corrosion process.

5

(e) During your course you planned and performed a first-hand investigation to

compare the rate of corrosion of different metals in acidic and neutral solutions.

(i) Outline the procedure you used in your investigation and describe the

results obtained.

3

(ii) While ocean water is slightly alkaline around a shipwreck the pH can be

lower.

Account for this observation.

2

Chemistry HSC Trial 2012

– 21 –

Question 34 — The Biochemistry of Movement (25 marks)

(a) Carbohydrates provide a significant proportion of an athlete’s energy needs.

(i) State the general formula for a carbohydrate.

1

(ii) Draw up a table showing the three main categories of carbohydrates and

name TWO examples of each.

4

(b) Tricylglycerols are a significant group of biological molecules.

(i) Name the TWO component molecules which make up tricylglycerols.

2

(ii) Outline TWO functions of tricylglycerols in organisms.

2

(c) Models are used to help understand and communicate complex ideas.

Discuss the use of models to aid understanding of enzyme function.

6

(d) (i) State the general formula for an amino acid.

1

(ii) Draw two amino acids linked together through the formation of a peptide

bond.

2

(iii) Which compounds can break peptide bonds in organisms?

1

(iv) Distinguish between the primary, secondary and tertiary structures of

proteins.

3

(e) Explain how the type of skeletal muscle fibres used varies with the nature of the

physical activity. 3

Chemistry HSC Trial 2012

– 22 –

Question 35 — The Chemistry of Art (25 marks)

(a) Outline the uses of pigments for body decoration or cosmetics by early Egyptian

or Roman cultures.

3

(b) The ground state electron configuration of chromium can be summarised as

2.8.13.1

(i) Outline why chromium can be classed as a d-block element.

1

(ii) Write the full ground state electron configuration of chromium showing all

sub-shells.

2

(iii) Explain why chromium has more than one oxidation state.

2

(c) During your course you performed a first-hand investigation to observe the flame

colour of a range of cations.

(i) Identify a risk in conducting this investigation and state a safety precaution

taken.

2

(ii) Outline your procedure and describe the results of your investigation.

3

(iii) Explain why excited atoms only emit certain frequencies of radiation.

2

(d) An element has successive ionisation energies shown in the following table.

Ionisation

Energy

(kJ mol-1

)

1st 2nd 3rd 4th 5th 6th 7th

744 1457 7739 10547 13636 18001 21710

(i) Predict the number of electrons in the outermost shell of this element.

1

(ii) Explain the relationship between number of electrons in the outer shell of

the element and its electronegativity.

3

(e) A painting on a wooden panel is offered for sale at auction as a medieval

religious artwork. The auction house suspects it could be a forgery and requests

testing to determine its age.

Discuss technologies chemists could use to identify the pigments in the painting

and estimate its age.

6

Chemistry HSC Trial 2012

– 23 –

Question 36 — Forensic Chemistry (25 marks)

(a) You performed a first-hand investigation to distinguish between reducing sugars

and non-reducing sugars.

(i) Outline the procedure you used in your investigation and describe the

results obtained.

3

(ii) Explain the chemical difference between reducing sugars and non-reducing

sugars.

2

(b) Assess the importance of accuracy and the prevention of contamination of

evidence in forensic analysis.

6

(c) Compare chromatography with electrophoresis focusing on the properties of

mixtures that are separated using these methods.

4

(d) Discuss the ethics of associated with storing an individual’s DNA in a data bank.

5

(e) (i) Outline how a mass spectrometer operates.

3

(ii) Describe TWO uses of mass spectroscopy in forensic analysis. 2

End of paper

Chemistry HSC Trial 2012

– 24 –

2012 TRIAL HIGHER SCHOOL CERTIFICATE EXAMINATION

Chemistry

DATA SHEET

Chemistry HSC Trial 2012

© Total Education Centre 2012 – 25 –

PERIODIC TABLE OF THE ELEMENTS KEY

1

H 1.008

Hydrogen

Atomic number

Chemical symbol

Relative atomic mass Name of element

2

He 4.003

Helium

3

Li 6.941

Lithium

4

Be 9.012

Beryllium

5

B 10.81

Boron

6

C 12.01

Carbon

7

N 14.01

Nitrogen

8

O 16.00

Oxygen

9

F 19.00

Fluorine

10

Ne 20.18 Neon

11

Na 22.99

Sodium

12

Mg 24.31

Magnesium

13

Al 26.98

Aluminium

14

Si 28.09

Silicon

15

P 30.97

Phosphorus

16

S 32.07 Sulfur

17

Cl 35.45

Chlorine

18

Ar 39.95 Argon

19

K 39.10

Potassium

20

Ca 40.08

Calcium

21

Sc 44.96

Scandium

22

Ti 47.87

Titanium

23

V 50.94

Vanadium

24

Cr 52.00

Chromium

25

Mn 54.94

Manganese

26

Fe 55.85 Iron

27

Co 58.93

Cobalt

28

Ni 58.69

Nickel

29

Cu 63.55

Copper

30

Zn 65.38

Zinc

31

Ga 69.72

Gallium

32

Ge 72.64

Germanium

33

As 74.92

Arsenic

34

Se 78.96

Selenium

35

Br 79.90

Bromine

36

Kr 83.80

Krypton

37

Rb 85.47

Rubidium

38

Sr 87.61

Strontium

39

Y 88.91

Yttrium

40

Zr 91.22

Zirconium

41

Nb 92.91

Niobium

42

Mo 95.96

Molybdenum

43

Tc

Technetium

44

Ru 101.1

Ruthenium

45

Rh 102.9

Rhodium

46

Pd 106.4

Palladium

47

Ag 107.9

Silver

48

Cd 112.4

Cadmium

49

In 114.8

Indium

50

Sn 118.7

Tin

51

Sb 121.8

Antimony

52

Te 127.6

Tellurium

53

I 126.9

Iodine

54

Xe 131.3 Xenon

55

Cs 132.9

Caesium

56

Ba 137.3

Barium

Lanthanoids

57-71

* -

72

Hf 178.5

Hafnium

73

Ta 180.9

Tantalum

74

W 183.9

Tungsten

75

Re 186.2

Rhenium

76

Os 190.2

Osmium

77

Ir 192.2

Iridium

78

Pt 195.1

Platinum

79

Au 197.0

Gold

80

Hg 200.6

Mercury

81

Tl 204.4

Thallium

82

Pb 207.2

Lead

83

Bi 209.0 Bismuth

84

Po

Polonium

85

At

Astatine

86

Rn

Radon

87

Fr

Francium

88

Ra

Radium

Actinoids

89-103

** -

104

Rf

Rutherfordium

105

Db

Dubnium

106

Sg

Seaborgium

107

Bh

Bohrium

108

Hs

Hassium

109

Mt

Meitnerium

110

Ds

Darmstadtium

111

Rg

Roentgenium

112

Cn

Copernicium

*Lanthanoids 57

La

138.9

Lanthanum

58

Ce

140.1

Cerium

59

Pr

140.9

Praseodymium

60

Nd 144.2

Neodymium

61

Pm

Promethium

62

Sm

150.4

Samarium

63

Eu

152.0

Europium

64

Gd

157.3

Gadolinium

65

Tb

158.9

Terbium

66

Dy

162.5 Dysprosium

67

Ho

164.9

Holmium

68

Er

167.3

Erbium

69

Tm

168.9

Thulium

70

Yb

173.1

Ytterbium

71

Lu

175.0

Lutetium

**Actinoids 89

Ac

Actinium

90

Th 232.0

Thorium

91

Pa 231.0

Protactinium

92

U 238.0

Uranium

93

Np

Neptunium

94

Pu

Plutonium

95

Am

Americium

96

Cm

Curium

97

Bk

Berkelium

98

Cf

Californium

99

Es

Einsteinium

100

Fm

Fermium

101

Md

Mendelevium

102

No

Nobelium

103

Lr

Lawrencium

Elements with atomic numbers 113 and above have been reported but not fully authenticated.

Standard atomic weights are abridged to four significant figures.

Elements with no reported values in the table have no stable nuclides.

Chemistry HSC Trial 2012

Student Number/Name………………………………

Class………………………………

2012 CHEMISTRY TRIAL HSC EXAMINATION

Section I – Part A Answer Sheet

20 marks

Attempt Questions 1 –20

Allow about 35 minutes for this section

Select the alternative A, B, C, or D that best answers the question. Fill in the response circle

completely.

1 A B C D

2 A B C D

3 A B C D

4 A B C D

5 A B C D

6 A B C D

7 A B C D

8 A B C D

9 A B C D

10 A B C D

11 A B C D

12 A B C D

13 A B C D

14 A B C D

15 A B C D

16 A B C D

17 A B C D

18 A B C D

19 A B C D

20 A B C D

Chemistry HSC Trial 2012

© Total Education Centre 2012 – 1 – Chemistry HSC Trial Marking Guidelines

2012 Chemistry HSC Trial Marking Guidelines

Section I — Part A

MULTIPLE CHOICE ANSWERS

1 A 6 D 11 B 16 A

2 C 7 B 12 C 17 B

3 B 8 A 13 D 18 B

4 D 9 A 14 A 19 B

5 A 10 D 15 C 20 A

Section I — Part B

Question 21

a

Criteria Marks

Provides definition of condensation polymer and a named example 2

Provides EITHER definition of condensation polymer OR a named

example

1

Suggested answer

A condensation polymer is one formed by the elimination of a small molecule (usually water) when

monomers bond together to form the polymer. An example is cellulose. Other examples are possible.

b

Criteria Marks

Gives correct name of monomer and structural formula 2

Gives EITHER correct name of monomer OR structural formula 1

Suggested answer

The monomer of cellulose is glucose

Chemistry HSC Trial 2012

© Total Education Centre 2012 – 2 – Chemistry HSC Trial Marking Guidelines

Question 22

Criteria Marks

Demonstrates thorough knowledge and understanding of two different

reactions used to produce ethanol and the various sources of reactants

Identifies uses of ethanol and relates to reactions

Explains and justifies the renewable or non-renewable nature of each

source of raw material

Provides correct equations for each reaction

6

Demonstrates sound knowledge and understanding of two different

reactions used to produce ethanol and the various sources of reactants

AND/OR uses of ethanol identified and related to reactions

Explains and justifies the renewable or non-renewable nature of each

source of raw material

Provides correct equations for each reaction

5

Demonstrates sound knowledge and understanding of one OR two

reactions used to produce ethanol and the various sources of reactants

AND/OR uses of ethanol identified and related to reactions

Explains the renewable or non-renewable nature of each source of raw

material

Provides one or two correct equation(s) provided

3-4

Provides some information on renewable OR non-renewable sources

of reactants for one OR two reactions used to produce ethanol

Provides a correct equation

2

Provides some information on renewable OR non-renewable sources

of reactants for a reaction used to produce ethanol.

1

Suggested answer

When ethene is used as a raw material to produce ethanol it is regarded as a non-renewable resource, if

the ethene is obtained from petroleum or natural gas. Fossil fuels such as petroleum or natural gas take

millions of years to form. Once they are used they cannot be replaced in a realistic time frame. The

ethanol produced as an industrial solvent is produced by the hydration of ethene.

Therefore, ethanol can be both a renewable and a non-renewable resource depending on the origin of

the reactants used to produce it.

Question 23

a

Criteria Marks

Provides correct equation:

Zn(s) + Ni+2

(aq) → Zn+2

(aq) + Ni(s)

1

b

Criteria Marks

Provides correct answer with unit and working out provided 2

Provides correct answer with unit OR working out with minor error 1

Suggested answer

Zn(s) → Zn+2

(aq) + 2e-

0.76 V

2e- + Ni

+2(aq) → Ni(s) - 0.26 V

0.76 + -0.26 = 0.50V

Chemistry HSC Trial 2012

© Total Education Centre 2012 – 3 – Chemistry HSC Trial Marking Guidelines

Question 24

Criteria Marks

Explains in detail the reactions which lead to the formation of acid rain

from at least two sources of acidic oxides.

Explains at least two effects of acid rain

4

Explains in detail the reactions which lead to the formation of acid rain

from at one source of acidic oxide and brief explanation of second

source.

Explains at least two effects of acid rain

3

Explains briefly the reactions which lead to the formation of acid rain

from at one or two sources of acidic oxides

AND/OR

Gives brief explanation of two acid rain effects

2

Explains briefly the reactions which lead to the formation of acid rain

from at one source of acidic oxides

OR

Gives brief explanation of two acid rain effects

1

Suggested answer

All rain is acidic; however acid rain has a pH less than 5. The rain becomes acidic when water reacts

with oxides of sulfur and nitrogen.Sulfur dioxide is produced when fossil fuels such as coal is burnt.

S (in coal) + O2 (g) → SO2(g)

Another source of sulfur dioxide is from metal extraction plants. For example

2ZnS(s) + 3O2 → 2ZnO(s) + 2SO2(g)

Sulfur dioxide then reacts with water droplets in the air to form sulphurous acid.

Acid rain can damage ecosystems by making soil and water in lakes too acidic to support healthy plant

and animal growth. Acid rain can also erode the built environment dissolving buildings and statues

made of marble or limestone.

Question 25 *

a)

b)

Chemistry HSC Trial 2012

© Total Education Centre 2012 – 4 – Chemistry HSC Trial Marking Guidelines

Question 26

a

Criteria Marks

Balances equation with subscripts shown below 1

Suggested answer

2NaOH(aq) + H2SO4(aq) → Na2SO4(aq) + 2H2O(g)

b

Criteria Marks

Calculates average titre calculated, then concentration of sulfuric acid -

working out shown with correct answer and unit supplied

3

As above with one omission of working out or unit 2

Calculates average titre 1

Suggested answer

Average titre = 29.0 mL

C x2 x 0.0290 = 0.20 x 0.025

C = 0.086 mol L-1

c

Criteria Marks

Explains how sodium hydroxide could have been standardised against

a suitable primary standard solution or a solution that had been titrated

against one

Recognises that sodium hydroxide could not be a primary standard

2

Explains how the concentration of sodium hydroxide could have been

calculated through titration

1

Suggested answer

Sodium hydroxide could have been titrated against a primary standard such as oxalic acid. Unlike

sodium hydroxide oxalic acid is a stable solid which can be accurately weighed to determine a known

number of moles and made into a solution of known concentration using a volumetric flask.

Chemistry HSC Trial 2012

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Question 27

a

Criteria Marks

Correctly names products as butyl methanoate and water 1

b

Criteria Marks

Justifies refluxing and use of concentrated sulfuric acid with detailed

evidence referring to equilibrium position in esterification reaction and

the use of catalyst

4

Justifies refluxing and use of concentrated sulfuric acid with evidence

referring to equilibrium position in esterification reaction and the use

of catalyst

3

Provides information on how refluxing works and what catalysts do to

reaction rates

2

Provides information on how refluxing works OR what catalysts do to

reaction rates

1

Suggested answer

Esterification is an equilibrium reaction which favours the reactants and is very slow. Concentrated

sulfuric acid is used as a catalyst to increase the reaction rate by lowering the activation energy. The

reaction rate and yield is increased by heating the reactants at higher temperatures in a flask connected

to a condenser so that volatile reactants cannot escape. The equilibrium position can be shifted to the

right by adding a reactant such as the alcohol in excess as predicted by Le Chatelier’s principle.

c

Criteria Marks

Identifies two hazards with two safety precautions described 2

Identifies one or two hazards with one or two safety precautions

described

1

Suggested answer

Multiple answers possible

Alcohol is flammable and can ignite if vapours are exposed to a flame. Refluxing can be done using a

water bath and a hotplate to reduce risk of fire. Concentrated sulfuric acid is highly corrosive and can

damage eyes and skin. Risk can be reduced by wearing safety glasses, suitable gloves and laboratory

coat.

Chemistry HSC Trial 2012

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Question 28 *

Chemistry HSC Trial 2012

© Total Education Centre 2012 – 7 – Chemistry HSC Trial Marking Guidelines

Question 29

Criteria Marks

Evaluates the significance of the Haber process in terms of at least two

criteria which are expanded upon demonstrating a thorough knowledge

and understanding

Includes chemical equation

Explains Haber process in terms of ammonia production from

atmospheric nitrogen

5

As above with one or two omissions 3-4

Explains briefly ammonia production linked to some related event in

early twentieth century world history without evaluation

2

Explains briefly ammonia production

OR

Identifies some related event in early twentieth century world history

1

Suggested answer

The Haber process for the production of ammonia from atmospheric nitrogen was a significant

breakthrough in chemistry having an enormous impact on early twentieth century world history.

N2(g) + 3H2(g) → 2NH3(g)

Haber solved the problem of the un-reactivity of nitrogen gas by manipulating the temperature and

pressure and the use of a catalyst.

Ammonia could be produced cheaply in vast quantities. This allowed the mass production of fertilizers

and explosives. The fertilizers increased the agricultural production of food crops avoiding famine.

This allowed world population to dramatically increase. The production of explosives allowed

Germany to continue to produce ammunition for the first World War even after the allies had blocked

their access to supplies of natural nitrates. This probably extended the war by up to two years leading

to the deaths of hundreds of thousands of people.

Chemistry HSC Trial 2012

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Question 30 *

a

b

\

Chemistry HSC Trial 2012

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Question 31 *

a

b

c

Chemistry HSC Trial 2012

© Total Education Centre 2012 – 10 – Chemistry HSC Trial Marking Guidelines

Section II — Electives

Question 32 (25 marks) – INDUSTRIAL CHEMISTRY

a(i)

Criteria Marks

Calculates correctly all initial concentrations and equilibrium

concentrations of each species

3

Calculates initial concentrations correctly with one error in equilibrium

concentrations

2

Two errors in calculations 1

Suggested answer

Volume of reaction vessel = 10 litres

species Moles initial conc.

mol L-1

equilibrium conc.

mol L-1

CO 2.0 0.20 0.10

Cl2 5.0 0.50 [Cl2] - [COCl2]

0.50 - 0.10 = 0.40

COCl2 1.0 0 0.20-0.10 =0.10

(ii)

Criteria Marks

Shows correct equilibrium expression and working out showing

correct equilibrium constant

2

Shows correct equilibrium expression shown OR equilibrium constant 1

Suggested answer

k = [COCl2] = 0.1____ = 2.5

[CO] [Cl2] 0.1 x 0.40

(ii)

Criteria Marks

Correctly predicts reaction direction with explanation 1

Suggested answer

When the temperature is lowered the reaction will shift to the right. The production of COCl2 is

exothermic so the reaction will move to raise the temperature by shifting to the right

(iv)

Criteria Marks

Correctly states change to constant when temperature is changed 1

Suggested answer

Changing the temperature will change the equilibrium constant to a higher number.

Chemistry HSC Trial 2012

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b (i)

Criteria Marks

Gives procedure outlines, equipment, solutions and steps undertaken in

sufficient detail to perform task

2

Gives brief procedure outlining steps 1

Suggested answer (Answers will vary)

1. Fill a Hofmann voltameter with 0.01 mol L-1

NaCl solution.

2. Connect voltameter to 12 volt D.C. power supply.

3. Place an inverted test tube over each of the taps, open to fill test tube with collected gases.

4. Test gases.

(ii)

Criteria Marks

Provides observations of gas properties and test results

Gives correct half equations at anode and cathode

3

Provides observations of gas properties and test results

Gives correct half equations at anode OR cathode

2

Provides observations of gas properties and test results 1

Suggested answer

At the cathode (-) a colourless gas which when tested with a flame gave a pop sound indicating

hydrogen was produced.

2H2O(l) + 2e- → H2(g) + 2OH

-(aq)

At the anode (+) a colourless gas which when tested with a flame, flared and burned brighter indicating

oxygen was produced.

2H2O(l) → O2(g) + 4H-(aq) + 4e

-

(iii)

Criteria Marks

Explains giving clear evidence why the nature of the products of

electrolysis change.

Correctly identifies changed products at anode

2

Correctly identifies changed products at anode 1

Suggested answer

As the concentration of the NaCl solution increases the products produced at the anode will change

producing a mixture of oxygen and chlorine gas. When using a concentrated solution of NaCl the

discharge of chlorine gas becomes more favourable.

2Cl- (aq) → Cl2(g) + 2e

- E

0 = -1.36 V

2H2O(l) → O2(g) + 4H-(aq) + 4e

- E

0 = -1.23 V

Chemistry HSC Trial 2012

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c

(i)

(ii)

Chemistry HSC Trial 2012

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d

(i)

(ii)