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GCE JAN 2007 : (AS 2) Organic, Physical and Inorganic Chemistry

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Centre Number 71 Candidate Number ADVANCED SUBSIDIARY (AS) General Certificate of Education January 2007 Chemistry assessing Module 2: Organic, Physical and Inorganic Chemistry ASC21 Assessment Unit AS 2 [ASC21] TUESDAY 23 JANUARY, MORNING 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. INFORMATION FOR CANDIDATES The total mark for this paper is 100. Quality of written communication will be assessed in question 15(a)(i). 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 pages indicate the marks awarded to each question or part question. A Periodic Table of Elements (including some data) is provided. For Examiner s use only Question Number Section A 1 10 Section B 11 12 13 14 15 16 Total Marks ASC2W7 2737 Marks BLANK PAGE ASC2W7 2737 2 [Turn over Section A For each of the following questions only one of the lettered responses (A D) is correct. Select the correct response in each case by connecting the dots as illustrated on the answer sheet. 1 Which one of the following is not the correct formula for a radical? A B C D 2 H Cl CH3 CH4 Which one of the following reaction profiles is correctly labelled and represents a combustion reaction? A B reactants products H H reactants products C D products H H reactants 3 reactants products Which one of the following is the number of structural isomers of butane? A B C D ASC2W7 1 2 3 4 2737 3 [Turn over 4 Which one of the following formulae represents a secondary alcohol? A H B H C C C2H5 OH H CH3 C OH OH CH3 H C H CH3 C D OH CH3 H C C2H5 H 5 Which one of the following reagents does not produce a gas when reacted with butanol? A B C D 6 OH hydrogen bromide phosphorus pentachloride sodium thionyl chloride Which one of the following ions produces a precipitate with magnesium ions? A B C D ASC2W7 CO32 HCO3 NO3 SO42 2737 4 [Turn over 7 Which pair of the following are cis-trans isomers? H Cl C C H Cl 8 C C H Cl 2 H 3 H C C Cl H Cl C H Cl 4 1 and 2 1 and 3 2 and 3 3 and 4 Which one of the following gases has no effect on damp Universal Indicator paper? A B C D 9 H Cl C 1 A B C D Cl ammonia chlorine hydrogen hydrogen chloride 2.1 g of an alkene, containing only one double bond per molecule, react completely with 8.0 g of bromine. Which one of the following is the molecular formula of the alkene? A B C D C2H4 C3H6 C4H8 C5H10 10 Which one of the following is removed from bromoethane when it is reacted with ethanolic sodium hydroxide? A B C D ASC2W7 Br2 H2O HBr NaBr 2737 5 [Turn over Section B Examiner Only Marks Remark Answer all six questions in the spaces provided 11 Using the words high and low complete the following table. Polythene Flexibility Softening temperature Chemical inertness high density low density [3] 12 The diagram below represents the industrial fractional distillation of crude oil. gases p____________ naphtha k____________ d____________ crude oil lubricating oil heater residue (a) (i) Complete the labels on the diagram. [3] (ii) What property of the fractions allows them to be separated? ____________________________________________________[1] ASC2W7 2737 6 [Turn over (b) Hydrocarbons in the C15 C19 range can be cracked by strong heating. The mechanism of cracking involves the formation of radicals. Examiner Only Marks Remark (i) Write the molecular formula for the alkene with 18 carbon atoms. ____________________________________________________[1] (ii) Explain the term radical. ______________________________________________________ ____________________________________________________[1] (iii) Write an equation for the cracking of C16H34 to produce ethene and propene in the molar ratio 2: 1 and only one other compound. ____________________________________________________[2] (iv) How could you demonstrate experimentally that unsaturated hydrocarbons are produced? ______________________________________________________ ____________________________________________________[2] ASC2W7 2737 7 [Turn over 13 Nitrogen dioxide may be prepared in the laboratory using the following apparatus. Examiner Only Marks Remark lead(II) nitrate oxygen test tube heat crushed ice + salt liquid NO2 trough water The lead(II) nitrate decomposes when heated. 2Pb(NO3)2 2PbO + 4NO2 + O2 (a) (i) How could you show that oxygen was collected in the test tube? ______________________________________________________ ____________________________________________________[2] (ii) Suggest why an ice salt mixture is needed to separate nitrogen dioxide from oxygen. ______________________________________________________ ____________________________________________________[1] (b) Nitrogen dioxide exists in dynamic equilibrium with dinitrogen tetraoxide. They have distinctive colours, NO2 is dark brown and N2O4 is yellow. N2O4 2NO2 H = +56 kJ (i) Explain the meaning of the term dynamic equilibrium. ______________________________________________________ ____________________________________________________[1] (ii) Explain the effect of an increase in temperature on the equilibrium. ______________________________________________________ ____________________________________________________[2] ASC2W7 2737 8 [Turn over (iii) Explain the effect of an increase in pressure on the equilibrium. Examiner Only Marks Remark ______________________________________________________ ____________________________________________________[2] (iv) The effect of pressure on the equilibrium can be demonstrated using a sealed syringe. cork plunger N2O4 2NO2 State what is seen in the syringe when the plunger is pushed in. ______________________________________________________ ____________________________________________________[1] (c) Nitrogen dioxide is produced in car engines. State how nitrogen dioxide is removed from car exhausts and what is formed. _________________________________________________________ _________________________________________________________ _______________________________________________________ [3] (d) In the laboratory nitrogen dioxide can be removed by passing the gas through sodium hydroxide solution. 2NO2 + 2NaOH NaNO2 + NaNO3 + H2O Calculate the volume of 2 M NaOH needed to react with 720 dm3 of nitrogen dioxide at 20 C and one atmosphere pressure using the following headings. (i) moles of nitrogen dioxide ____________________________________________________[1] (ii) moles of sodium hydroxide required ____________________________________________________[1] (iii) volume of 2 M NaOH required ____________________________________________________[1] ASC2W7 2737 9 [Turn over 14 Alpha hydroxyacids (AHAs) are used in low concentrations (1%) in skin creams to remove wrinkles. More concentrated solutions (12%) remove dead skin. Two AHAs are glycolic acid and lactic acid. CH2OHCOOH Remark CH3CHOHCOOH glycolic acid Examiner Only Marks lactic acid (a) One of these molecules will undergo a positive iodoform test. (i) Explain, in structural terms, which one of the molecules would give a positive test. ______________________________________________________ ____________________________________________________[1] (ii) Describe how you would carry out an iodoform test and state the result for a positive test. ______________________________________________________ ______________________________________________________ ______________________________________________________ ____________________________________________________[3] ASC2W7 2737 10 [Turn over (b) The OH group in glycolic acid acts in the same way as in a primary alcohol. Complete the following flow scheme by drawing the structures of the organic products. CH3CO2H H+/Cr2O72 HBr H+/Cr2O72 CH2OHCOOH Examiner Only Marks Remark [4] (c) Calculate the molarity of a 12%, by mass, solution of lactic acid in water. Assume 100 g of water is 100 cm3. _________________________________________________________ _________________________________________________________ _______________________________________________________ [3] ASC2W7 2737 11 [Turn over 15 The hydroxides of the Group II metals, magnesium to barium, are white ionic solids. They are sparingly soluble in water, the solubility rising with atomic number. Examiner Only Marks Remark g/100 cm3 water at 25 C Mg(OH)2 Ca(OH)2 Sr(OH)2 Ba(OH)2 0.01 0.15 0.89 3.32 (a) (i) Suggest how you could determine the solubility of strontium hydroxide at 25 C. Give full practical details. ______________________________________________________ ______________________________________________________ ______________________________________________________ ______________________________________________________ ____________________________________________________[3] Quality of written communication [2] (ii) Explain this solubility trend of the hydroxides using enthalpy considerations. ______________________________________________________ ____________________________________________________[2] (iii) Calculate the molar concentration of hydroxide ions in a saturated solution of magnesium hydroxide which contains 1.72 10 3 mol dissolved in 100 cm3 of water. ______________________________________________________ ____________________________________________________[2] ASC2W7 2737 12 [Turn over (iv) Use the following headings to calculate the volume of carbon dioxide needed to precipitate out all of the calcium ions in 100 cm3 of a saturated solution of calcium hydroxide at 25 C and one atmosphere pressure. Examiner Only Marks Remark Ca(OH)2 + CO2 CaCO3 + 2H2O relative formula mass of Ca(OH)2 ______________________________________________________ moles of Ca(OH)2 in 100 cm3 of water. ______________________________________________________ moles of CO2 reacting with the Ca(OH)2 ______________________________________________________ volume of CO2, in cm3, reacting with the Ca(OH)2 ____________________________________________________[4] (b) Barium hydroxide reacts with dilute nitric acid to give a solution of barium nitrate. (i) Write an equation for the reaction. ____________________________________________________[2] (ii) Barium nitrate is used as a component of coloured flares. What is the colour produced? ____________________________________________________[1] (iii) Explain why barium hydroxide does not dissolve in dilute sulphuric acid. ______________________________________________________ ____________________________________________________[1] ASC2W7 2737 13 [Turn over (c) Barium hydroxide decomposes on heating. However, it melts before it decomposes, whereas calcium hydroxide does not. Examiner Only Marks Remark (i) State the trend in thermal stability of the Group II hydroxides. ____________________________________________________[1] (ii) State the two factors that determine the thermal stability of Group II metal hydroxides. ______________________________________________________ ____________________________________________________[2] (d) Barium carbonate decomposes in a similar way to that of barium hydroxide. (i) Write an equation for the decomposition. ____________________________________________________[1] (ii) Describe a positive test for the carbon dioxide given off. ______________________________________________________ ____________________________________________________[2] ASC2W7 2737 14 [Turn over 16 Catalysts come in many forms. Sometimes they are inorganic, e.g. finely divided transition metals or metal compounds or even acids which do not contain metals, or they may be organic macromolecules. Examiner Only Marks Remark (a) Name the following catalysts. (i) The element which acts as a catalyst in reducing the ozone layer. ____________________________________________________[1] (ii) The metal used in the hardening of oils. ____________________________________________________[1] (iii) The metal which acts as a catalyst in the Haber process. ____________________________________________________[1] (iv) The metal oxide used in the Contact process. ____________________________________________________[1] (v) The acid used as a catalyst in esterification reactions. ____________________________________________________[1] (b) Explain, using a reaction profile, how catalysts provide an alternative reaction pathway with a lower activation energy. _________________________________________________________ _______________________________________________________ [3] ASC2W7 2737 15 [Turn over (c) (i) What is the name given to a biological catalyst? Examiner Only Marks Remark ____________________________________________________[1] (ii) Explain what is meant by the term active site in a biological catalyst. ______________________________________________________ ____________________________________________________[2] (d) Catalysts are used in the production of high density polythene. Suggest why the use of a catalyst leads to the formation of HD polythene and not LD polythene. _________________________________________________________ _______________________________________________________ [1] (e) Light is sometimes wrongly regarded as a catalyst in the chlorination of methane. Using a definition of a catalyst, explain why light is not a catalyst. _________________________________________________________ _______________________________________________________ [2] (f) Catalysis can either be homogeneous or heterogeneous. (i) Explain what is meant by the term homogeneous catalysis. ______________________________________________________ ____________________________________________________[2] (ii) Give one example of a reaction involving homogeneous catalysis. ____________________________________________________[1] (iii) Give one example of a reaction involving heterogeneous catalysis. ____________________________________________________[1] ASC2W7 2737 16 [Turn over THIS IS THE END OF THE QUESTION PAPER S 6/06 2000 9-045-1 [Turn over

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Additional Info : Gce Chemistry January 2007 Assessment Unit AS 2Module 2: Organic, Physical and Inorganic Chemistry
Tags : General Certificate of Education, A Level and AS Level, uk, council for the curriculum examinations and assessment, gce exam papers, gce a level and as level exam papers , gce past questions and answer, gce past question papers, ccea gce past papers, gce ccea past papers

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