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This publication may be reproduced only in accordance with Edexcel Limited copyright policy. ©2007 Edexcel Limited. Printer’s Log. No. N23595A W850/U7081/57570 3/3/3/2/2/1400 Paper Reference(s) 7081/02 London Examinations GCE Chemistry Ordinary Level Paper 2 Monday 22 January 2007 – Afternoon Time: 2 hours Materials required for examination Items included with question papers Nil Nil Instructions to Candidates The paper is arranged in two sections, A and B. In Section A, answer ALL questions. In Section B, answer TWO questions. In the boxes above, write your centre number, candidate number, your surname, initial(s) and signature. Information for Candidates A Periodic Table is printed on the back cover of this booklet. Calculators may be used. The total mark for this paper is 100. Marks for parts of questions are shown in round brackets: e.g. (2). This paper has nine questions. DATA One mole of any gas occupies 24 000 cm 3 at room temperature and atmospheric pressure. One mole of electrons carries a charge of 96 500 coulombs or 1 faraday. Advice to Candidates Write your answers neatly and in good English. In Section B, organise your material and present your ideas in a clear and logical form. In calculations, show all the steps in your working. Turn over Examiner’s use only Team Leader’s use only Question Leave Number Blank 1 2 3 4 5 6 7 8 9 Total Centre No. Candidate No. Surname Initial(s) Signature *N23595A0120* www.XtremePapers.net

Transcript of 7081_02_que_20070122

Page 1: 7081_02_que_20070122

This publication may be reproduced only in accordance with Edexcel Limited copyright policy. ©2007 Edexcel Limited.

Printer’s Log. No.

N23595AW850/U7081/57570 3/3/3/2/2/1400

Paper Reference(s)

7081/02London Examinations GCEChemistryOrdinary LevelPaper 2Monday 22 January 2007 – AfternoonTime: 2 hours

Materials required for examination Items included with question papersNil Nil

Instructions to CandidatesThe paper is arranged in two sections, A and B.In Section A, answer ALL questions.In Section B, answer TWO questions.In the boxes above, write your centre number, candidate number, your surname, initial(s) and signature.

Information for CandidatesA Periodic Table is printed on the back cover of this booklet.Calculators may be used.The total mark for this paper is 100. Marks for parts of questions are shown in round brackets: e.g. (2).This paper has nine questions.DATAOne mole of any gas occupies 24 000 cm3 at room temperature and atmospheric pressure.One mole of electrons carries a charge of 96 500 coulombs or 1 faraday.

Advice to CandidatesWrite your answers neatly and in good English.In Section B, organise your material and present your ideas in a clear and logical form.In calculations, show all the steps in your working.

Turn over

Examiner’s use only

Team Leader’s use only

Question LeaveNumber Blank

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Total

CentreNo.

Candidate No.

Surname Initial(s)

Signature

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SECTION A

Answer ALL questions in this section. Write your answers in the spaces provided.

There is useful data on the front cover, and a Periodic Table is printed on the back ofthis booklet.

1. For each of the following reactions involving transition metal compounds:

• describe what you would see• identify the product that contains the transition metal ion• write an equation for the reaction if required.

(a) Aqueous sodium hydroxide is added to aqueous iron(III) chloride.

Observation ...................................................................................................................

Name of product ...........................................................................................................

Equation ........................................................................................................................(3)

(b) A few drops of aqueous ammonia are added to aqueous copper(II) sulphate followedby an excess of ammonia.

Observation after adding a few drops of ammonia ......................................................

Name of product ...........................................................................................................

Observation after adding excess ammonia ...................................................................

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Formula of complex ion product ..................................................................................(4)

(c) Copper(II) carbonate is heated strongly.

Observation ...................................................................................................................

Name of product ...........................................................................................................

Equation ........................................................................................................................(3) Q1

(Total 10 marks)

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2. (a) For each of the following covalent molecules, draw a dot and cross diagram to showthe outer shell electron arrangement and a diagram to show the shape.

(i) ammonia, NH3

electron arrangement shape

(ii) carbon dioxide, CO2

electron arrangement shape

(6)

(b) (i) State which particle in the nucleus of an atom is responsible for the positionof an element in the Periodic Table.

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(ii) State which particle in the nucleus of an atom is responsible for the isotopeshaving different mass numbers.

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(iii) State how the position of an element in the Periodic Table is related to its electronconfiguration, and give an example.

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Q2

(Total 10 marks)

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3. This question refers to the three organic compounds labelled A, B and C below.

Compound A Compound B Compound C

CH3CH=CHCOOH CH3CH2CH2COOH CH3CH=CHCH2OH

(a) Which one of the compounds has a relative molecular mass of 86?

.......................................................................................................................................(1)

(b) Compounds B and C could react together to form an ester. Give the two conditionsused for this reaction.

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(c) Aqueous sodium carbonate was added to each compound.

(i) State which of the compounds A, B and C would react with sodium carbonate togive carbon dioxide.

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(ii) Describe a test for carbon dioxide.

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(d) Each compound was shaken with bromine water.

(i) State which of the compounds A, B and C would decolourise the bromine water.

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(ii) Identify the structural feature that is responsible for the decolourisation ofbromine water.

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(iii) State the type of reaction occurring when bromine water is decolourised.

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(iv) Write an equation for the reaction between bromine and one of the compounds.

................................................................................................................................(1) Q3

(Total 10 marks)

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4. (a) You are provided with bromine water, aqueous sodium chloride and aqueous sodiumiodide, together with a supply of test tubes. Using these solutions only, describe twoexperiments to show the relative reactivity of chlorine, bromine and iodine.

For each experiment, describe what you would do and what observation you wouldmake. State how the results of the experiments confirm the relative reactivity andwrite an equation for any reaction that occurs.

Experiment 1

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Experiment 2

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(b) State how the addition of aqueous silver nitrate to aqueous sodium chloride and toaqueous sodium iodide would enable you to distinguish between the two compounds.

Observation with NaCl(aq): .........................................................................................

Observation with NaI(aq): ............................................................................................(2)

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Q4

(Total 10 marks)

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5. The reaction which produces methanol from carbon monoxide and hydrogen isrepresented by the equation

CO(g) + 2H2(g) CH3OH(g) ∆H = –94kJ mol–1

The reaction is carried out at high pressure and the gases are passed through a mixture ofzinc oxide and chromium oxide maintained at 400 °C. These conditions are chosen togive a good yield of methanol at a satisfactory rate.

(a) (i) Explain why increasing the pressure gives a better yield.

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(ii) Give one disadvantage of using high pressure in an industrial plant.

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(b) (i) The value of ∆H is negative. What does this tell you about the reaction?

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(ii) State, with a reason, whether a high temperature or low temperature will give abetter yield of methanol at equilibrium.

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(iii) With reference to your answer in (b)(ii), suggest why a temperature of 400 °C isused in practice.

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(c) Suggest why the gases are passed through a mixture of zinc oxide and chromium oxide.

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(d) Calculate the maximum mass of methanol that can be obtained from 14 kg of carbon monoxide.

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TOTAL FOR SECTION A: 50 MARKS

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Q5

(Total 10 marks)

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SECTION B

Answer TWO questions in this section. If you change your mind, put a line throughthe box ( ) and then indicate your new question with a cross ( ).

Where appropriate, give equations and diagrams to clarify your answers.

If you answer question 6 put a cross in this box

6. (a) Describe how you would prepare crystals of each salt using the method indicated.Write an equation for each reaction.

(i) Sodium nitrate, NaNO3, by reacting an acid with an alkali.

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(ii) Anhydrous iron(III) chloride, FeCl3, by direct reaction of the elements.

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(iii) Copper(II) sulphate, CuSO4.5H2O, by reacting an acid with a metal oxide.

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(b) The mineral kieserite has the formula MgSO4.H2O.

(i) Calculate the percentage by mass of magnesium in kieserite.

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(ii) Describe one test to show that kieserite contains sulphate ions.

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................................................................................................................................(4) Q6

(Total 25 marks)

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If you answer question 7 put a cross in this box

7. (a) Describe the reactions of sodium and potassium with water, giving three similaritiesand one difference. Write an equation for one of the reactions.

Explain, in terms of their electronic configurations, why the elements sodium andpotassium have similar chemical properties. State the trend in reactivity ondescending Group 1 and suggest a reason for it.

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(b) Rubidium, Rb, is the fourth member of Group 1. Name the products and write anequation for any reaction that occurs when the following compounds are heated:

(i) rubidium carbonate;

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(ii) rubidium nitrate.

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(c) Aqueous sodium chloride (brine) containing litmus indicator is electrolysed inapparatus that prevents the products formed at the electrodes from mixing. Theindicator turns blue near the cathode and colourless near the anode.

(i) Write an equation for the reaction occurring at the anode and explain why thelitmus turns colourless.

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(ii) Write an equation for the reaction occurring at the cathode and explain why thelitmus turns blue. What other observation would you see at the cathode?

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(iii) Name an important compound that is produced industrially by the electrolysis ofbrine and give one large-scale use for it.

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(d) Describe a simple experiment to show whether a white powder is a sodiumcompound or a potassium compound.

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Q7

(Total 25 marks)

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If you answer question 8 put a cross in this box

8. Crude oil is a source of many compounds that are of great importance in the chemicalindustry. Study the scheme below and answer the questions that follow.

(a) Give the name of Process A. Describe how the process of separating crude oil intofractions, including naphtha, is carried out.

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crude oil naphthaC6H14 – C10H22

etheneC2H4

ethanolC2H5OH poly(ethene) compound E

Process A

Process B

OxidationReaction C Reaction D

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(b) Give the name of Process B, in which the naphtha fraction is converted into manydifferent compounds, including ethene. Describe how this is done and explain whathappens to the original molecules present in the naphtha. State the importance of thisprocess in the petrochemical industry.

Write an equation using C6H14 to show the formation of ethene and one othercompound.

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(c) Describe how ethene is converted into ethanol in Reaction C. Write an equation forthe reaction, using displayed formulae.

Give one advantage and one disadvantage that this method of producing ethanol hasover the fermentation method.

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(d) Name the type of polymerisation taking place in Reaction D. Draw the repeatingunit of the polymer.

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(e) Compound E has the following percentage composition by mass:

C = 38.7% H = 9.7% O = 51.6%

(i) Use these figures to calculate the empirical formula of E.

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(ii) Given that 0.05 mol of E has a mass of 3.1 g, calculate the relative molecularmass of E and hence determine its molecular formula.

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(Total 25 marks)

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If you answer question 9 put a cross in this box

9. Use your knowledge of structure and bonding to explain each of the followingobservations.

(a) Diamond is one of the hardest substances known whereas graphite is softand is used in pencils.

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(b) Sodium metal is a good conductor of electricity when solid and when molten.Sodium chloride does not conduct electricity when solid but does when molten.

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(c) At room temperature, MgO is a solid with a high melting point whereasH2O is a liquid that vaporises easily.

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(d) Argon and nitrogen are both unreactive at room temperature. Nitrogen will combinewith other elements at high temperature.

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(e) There is more than one compound with the molecular formula C2H4Cl2.

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TOTAL FOR SECTION B: 50 MARKS

END

Turn over

Q9

(Total 25 marks)

*N23595A01920*

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