unit 1 test paper

8/10/2019 Unit 1 Test Paper

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Each question or incomplete statement is followed by four suggestedanswers, A, B, C or D. Select the best answer in each case.The answersare given, with some commentary, after Question 10.


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Question 11

Crude oil contains a large proportion of alkanes, which form ahomologous series.a (i) Explain the meaning of the term homologous series, using thealkanes as your example. (2 marks)

(ii)Alkanes exhibit structural isomerism. Draw the skeletal formulae ofthe three structural isomers of the alkane C5H12. (3 marks)


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bMethane reacts with chlorine in the presence of ultraviolet light to givechloromethane and hydrogen chloride:

(i) What type of reaction is this? (1 mark)

.(ii) The first step of the mechanism involves homolytic fission. Explain

the meaning of the term homolytic fission. (1 mark)

(iii) Give the mechanism for the reaction between methane and chlorine,making clear which are the initiation, propagation and termination steps.Showing movement of electrons clearly.(6 marks)

Initiation(one equation):

Propagation(two equations):

Termination(three equations)

Total: 13 marks


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Question 12a State Hesss law. (2 marks)

b Define the term standard enthalpy of combustion, making clear themeaning of standard in this context. (3 marks)

c The equation for the combustion of ethanol in air is:C2H5OH(l) + 3O2(g) 2CO2(g) + 3H2O(l)Calculate the enthalpy change for this reaction using the average bond

enthalpy values given in the table.

Covalent bonds in all molecules


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Bond breaking:

Bond making:

Enthalpy change:


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Question 13a (i) Write the Complete electronic configuration of a sulfur atom:(1 mark)

(ii) State the number of neutrons in the nucleus of an atom of .(1 mark)

b (i) Define the term first electron affinity. (2 marks)

(ii) The following equation represents the change occurring when thesecond electron affinity of sulfur is measured:

Explain why the second electron affinity of an element is alwaysendothermic. (2 marks)

Total: 6 marks


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Question 14a When a sample of copper is analysed using a mass spectrometer, itsatoms are ionised, accelerated, and then separated according to theirmass/charge (m/e) ratio.

(i) Explain how the atoms of the sample are ionised. (2 marks)

(ii) State how the resulting ions are accelerated. (1 mark)

(iii) State how the ions are separated according to theirm/e values.(1 mark)

b For a particular sample of copper, two peaks were obtained in themass spectrum, showing an abundance of 69.10% at m/e 63 and30.90% at m/e 65.(i) Give the formula of the species responsible for the peak atm/e 65.

(1 mark)


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(ii) State why two peaks, at m/e values of 63 and 65,were obtained inthe mass spectrum. (1 mark)

(iii) Calculate the relative atomic mass of this sample of copper to threesignificant figures, using the data given above. (2 marks)

Total: 8 marks


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Question 15a (i) Describe one piece of evidence for the nature of the bonding insodium chloride. (2 marks)

(ii) Explain, in terms of its bonding and structure, why the meltingtemperature of sodium chloride is high. (3 marks)


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b Explain, in terms of its structure and bonding,why aluminium is a goodconductor of electricity. (3 marks)

c Draw a dot-and-cross diagram for iodine, I2, showing the outerelectrons only. (2 marks)

Total: 11 marks

unit 1 test paper

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