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GCE JUN 2008 : (AS 2) Organic, Physical and Inorganic Chemistry

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Centre Number 71 Candidate Number ADVANCED SUBSIDIARY (AS) General Certificate of Education 2008 Chemistry assessing Module 2: Organic, Physical and Inorganic Chemistry ASC21 Assessment Unit AS 2 [ASC21] THURSDAY 12 JUNE, AFTERNOON TIME 1 hour 30 minutes. INSTRUCTIONS TO CANDIDATES Write your Centre Number and Candidate Number in the spaces provided at the top of this page. Answer all sixteen questions. Answer all ten questions in Section A. Record your answers by marking the appropriate letter on the answer sheet provided. Use only the spaces numbered 1 to 10. Keep in sequence when answering. Answer all six questions in Section B. Write your answers in the spaces provided in this question paper. For Examiner s use only Question Number Marks Section A 1 10 Section B INFORMATION FOR CANDIDATES The total mark for this paper is 100. Quality of written communication will be assessed in question 14(e)(ii). In Section A all questions carry equal marks, i.e. two marks for each question. In Section B the figures in brackets printed down the right-hand side of the pages indicate the marks awarded to each question or part question. A Periodic Table of Elements (including some data) is provided. ASC2S8 3563 11 12 13 14 15 16 Total Marks BLANK PAGE ASC2S8 3563 2 [Turn over Section A For each of the questions only one of the lettered responses (A D) is correct. Select the correct response in each case and mark its code letter by connecting the dots as illustrated on the answer sheet. 1 What is the order of increasing boiling points for the following fractions when crude oil is distilled? A B C D 2 Which one of the following molecules exists as cis-trans isomers? A B C D 3 Bitumen, lubricating oil, kerosene, gasoline. Gasoline, kerosene, lubricating oil, bitumen. Kerosene, bitumen, gasoline, lubricating oil. Lubricating oil, gasoline, bitumen, kerosene. (CH3)2C = C(CH3)2 CH3CH2CH = CHCH2CH3 CH3CH2CH = C(CH3)2 (CH3)2CHCH2CH = CH2 Which one of the following represents the conditions used in the Contact Process? Catalyst Iron 001 2000 250 B Iron 200 1000 450 C Vanadium(V) oxide 001 2000 450 D 3563 Approximate temperature ( C) A ASC2S8 Approximate pressure (atm) Vanadium(V) oxide 200 1000 250 3 [Turn over 4 What is the systematic name for the molecule shown below? CH2CH3 CH3 CHCH2CH CH3 CH3 A B C D 5 The solubility of ethanol in water is due to A B C D 6 covalent bonding only. hydrogen bonding only. permanent dipole attractions. van der Waals forces. Which statement describes the pattern of the melting points for the elements in Group II? A B C D 7 2,4-dimethylhexane 2-ethyl-4-methylpentane 2-methyl-4-ethylpentane 3,5-dimethylhexane They decrease as the atomic number increases. They increase as the atomic number increases. They decrease from magnesium to calcium and then increase. They increase from magnesium to calcium and then decrease. It is important to minimise the release of sulphur dioxide during the manufacture of sulphuric acid as it can contribute to A B C D ASC2S8 acid rain. depletion of the ozone layer. global warming. increasing smog levels. 3563 4 [Turn over 8 Which one of the following will give a yellow precipitate in the iodoform test? A B C D 9 propan-1-ol propan-2-ol 2-methylpropan-1-ol 2-methylpropan-2-ol In propanone, CH3COCH3, the attractions between the molecules are A B C D dipole dipole attractions. dipole dipole attractions and hydrogen bonds. dipole dipole attractions and van der Waals forces. hydrogen bonds and van der Waals forces. 10 Which one of the following is a tertiary alcohol? A B C D ASC2S8 2-methylbutan-1-ol 2-methylbutan-2-ol 3-methylbutan-2-ol 2,2-dimethylpropan-1-ol 3563 5 [Turn over Section B Examiner Only Marks Remark Answer all six questions in this section. 11 Complete the table below by describing an appropriate test and the observation expected to identify each gas. Gas Test Observation Hydrogen Sulphur dioxide Hydrogen chloride [6] 12 The chlorination of methane in sunlight occurs by a free radical mechanism. (a) Explain what is meant by the term free radical. _______________________________________________________ [1] (b) Write the equation for the formation of chloromethane from chlorine and methane. _______________________________________________________ [1] (c) Write equations for each of the following stages in the reaction mechanism. (i) The initiation step. ____________________________________________________ [1] (ii) Two propagation steps. ______________________________________________________ ____________________________________________________ [2] (iii) One termination step. ____________________________________________________ [1] ASC2S8 3563 6 [Turn over 13 Deposits of limestone, which is mainly calcium carbonate, CaCO3, are found in Northern Ireland at the Marble Arch Caves and at White Park Bay. Examiner Only Marks Remark (a) Describe how you could show the presence of calcium ions and carbonate ions in a sample of limestone. calcium ions: __________________________________________________________ __________________________________________________________ __________________________________________________________ carbonate ions: __________________________________________________________ __________________________________________________________ _______________________________________________________ [4] (b) Calcium carbonate can be decomposed by heat. (i) Write an equation for the decomposition of calcium carbonate. ____________________________________________________ [1] (ii) Compare the thermal stability of calcium carbonate with those of magnesium and strontium carbonates, explaining any differences. ______________________________________________________ ______________________________________________________ ______________________________________________________ ____________________________________________________ [3] ASC2S8 3563 7 [Turn over (c) The percentage of calcium carbonate in a sample of limestone can be determined as follows: Examiner Only Marks Remark The sample of limestone is weighed and dissolved in excess hydrochloric acid. The unreacted hydrochloric acid is then titrated with standard sodium hydroxide solution. CaCO3 HCl + + CaCl2 + H2O NaOH NaCl + H2O 2HCl + CO2 1.05 g of limestone were dissolved in 30.0 cm3 of 1.0 M hydrochloric acid. The solution was then made up to 250 cm3. 25.0 cm3 of this solution, when titrated, required exactly 11.6 cm3 of 0.1 M sodium hydroxide solution. (i) Name a suitable indicator for the titration and give the colour change observed at the end point. Indicator: ______________________________________________ Colour change: from _______________________ to ______________________ [3] (ii) Calculate the percentage of calcium carbonate in the sample of limestone. Number of moles of sodium hydroxide used in the titration: ______________________________________________________ Number of moles of hydrochloric acid in 250 cm3 of solution: ______________________________________________________ Number of moles of hydrochloric acid in 30.0 cm3 of 1.0 M solution: ______________________________________________________ Moles of hydrochloric acid which reacted with the limestone: ______________________________________________________ Moles of calcium carbonate in the sample: ______________________________________________________ ASC2S8 3563 8 [Turn over Mass of calcium carbonate in the sample: Examiner Only Marks Remark ______________________________________________________ Percentage of calcium carbonate in the sample: ____________________________________________________ [5] ASC2S8 3563 9 [Turn over 14 Alkenes are important raw materials in the chemical industry. Examiner Only Marks Remark (a) Alkenes can be made from alkanes with high relative molecular masses, e.g. dodecane, C12H26. (i) What is the name given to this process? ____________________________________________________ [1] (ii) Write an equation for the formation of ethene from dodecane. ____________________________________________________ [1] (iii) Describe the chemical test to confirm the presence of an alkene in the resulting mixture. ______________________________________________________ ____________________________________________________ [2] (b) Ethene can also be prepared from bromoethane. Write an equation for this reaction, giving the reaction conditions. __________________________________________________________ _______________________________________________________ [2] ASC2S8 3563 10 [Turn over (c) Consider the following table. Examiner Only Marks Ethane Bond length/nm Bond energy/kJ mol 1 Ethene 0.154 0.134 346 Remark 598 (i) Explain the differences in bond length and bond energy in terms of the sigma ( ) and pi ( ) bonds present. ______________________________________________________ ______________________________________________________ ______________________________________________________ ____________________________________________________ [3] (ii) Explain why ethene is more reactive than ethane despite its bond energy being greater. ______________________________________________________ ______________________________________________________ ____________________________________________________ [2] (d) Hydrogen bromide, HBr, reacts readily with ethene. (i) Draw the mechanism for this reaction. [3] (ii) What name is used to describe this mechanism? ____________________________________________________ [2] ASC2S8 3563 11 [Turn over (e) Ethene may be polymerised to form high density (HD) or low density (LD) polythene. Examiner Only Marks Remark (i) What conditions are used for the manufacture of HD polythene? ______________________________________________________ ____________________________________________________ [2] (ii) By comparing their structures, explain the differences in softening temperature and flexibility of HD and LD polythene. ______________________________________________________ ______________________________________________________ ______________________________________________________ ______________________________________________________ ______________________________________________________ ______________________________________________________ ____________________________________________________ [4] Quality of written communication [2] (iii) Polymer waste may be disposed of in landfill sites or by incineration. State one advantage and one disadvantage of each method of disposal. Landfill: ______________________________________________ ______________________________________________________ ______________________________________________________ Incineration: ___________________________________________ ______________________________________________________ ____________________________________________________ [4] ASC2S8 ASC2S8 3563 12 [Turn [Turn over 15 Alcohol (ethanol) continues to play an important role in everyday life and in the laboratory. Examiner Only Marks Remark (a) Ethanol is considered to be a recreational drug. State one beneficial and one harmful effect of alcohol consumption. __________________________________________________________ __________________________________________________________ _______________________________________________________ [2] (b) Ethanol produced from sugar cane can be used as a fuel. (i) Write an equation for the complete combustion of ethanol. ____________________________________________________ [2] (ii) Give two environmental advantages of using ethanol as a fuel. ______________________________________________________ ____________________________________________________ [2] (c) Complete the diagram below by drawing the structure of each organic product formed. Na H+/Cr2O72 CH3CH2OH CH3COCl PCl5 [4] ASC2S8 3563 13 [Turn over 16 Nitrogen(II) oxide, NO, is produced in car engines and may be removed from the exhaust gases to help reduce air pollution. Examiner Only Marks Remark (a) The catalytic converter in a car exhaust converts the nitrogen(II) oxide to nitrogen by reacting it with carbon monoxide which is also present in the exhaust gases. (i) Write an equation for the reaction of nitrogen(II) oxide with carbon monoxide. ____________________________________________________ [2] (ii) On the axes below sketch the distribution of molecular kinetic energies in a gas and mark the activation energy, EA, of the uncatalysed and catalysed, EA(cat) reactions. number of molecules kinetic energy [3] (iii) Catalytic converters in car exhaust systems may contain platinum and palladium which act as heterogeneous catalysts. Using chemisorption, explain their catalytic behaviour. ______________________________________________________ ______________________________________________________ ____________________________________________________ [3] ASC2S8 3563 14 [Turn over (b) Nitrogen(II) oxide reacts with oxygen in the following equilibrium. Examiner Only Marks 2NO(g) + O2(g) Remark 2NO2(g) H = 114 kJ Describe and explain the effect of the following changes on the composition of the equilibrium mixture. (i) Increasing the temperature. ______________________________________________________ ____________________________________________________ [2] (ii) Increasing the pressure. ______________________________________________________ ____________________________________________________ [2] (iii) Adding a catalyst. ______________________________________________________ ____________________________________________________ [2] ASC2S8 3563 15 [Turn over S 3/07 531-007-1 16 [Turn over

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Additional Info : Gce Chemistry June 2008 Assessment Unit AS 2Module 2: Organic, Physical and Inorganic Chemistry
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