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GCE JAN 2007 : (A2 1) Further Organic, Physical and Inorganic Chemistry

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Centre Number 71 Candidate Number ADVANCED General Certificate of Education January 2007 assessing Module 4: Further Organic, Physical and Inorganic Chemistry A2C11 Chemistry Assessment Unit A2 1 [A2C11] THURSDAY 11 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. For Examiner s use only Question Number Marks Section A 1 10 INFORMATION FOR CANDIDATES The total mark for this paper is 90. Quality of written communication will be assessed in question 15(c)(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. Section B 11 12 13 14 15 16 Total Marks A2C1W7 2738 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 Which one of the following alcohols does not undergo oxidation when treated with warm acidified potassium dichromate(VI)? A B C D 2 Toothpaste for sensitive teeth contains 10% by mass of hydrated strontium chloride, SrCl2.6H2O. What is the mass of strontium contained in 100 g of toothpaste? A B C D 3 3-methylpentan-1-ol 3-methylpentan-2-ol 2-methylpentan-2-ol 2-methylpentan-1-ol 1.8 g 3.3 g 3.8 g 4.6 g Which one of the following does not contain an asymmetric centre? A B C D A2C1W7 CH3CH(CH3)CH2CH3 CH3CH(OH)CH2CH3 CH3CHClCH2CH3 CH3CH(NH2)CH2CH3 2738 2 [Turn over 4 Chlorine reacts with water according to the equation below. HOCl + H+ + Cl Cl2 + H2O Which one of the following substances when added would move the equilibrium to the right? A B C D 5 The concentration of hydrogen ions in a solution is 1 10 6 mol dm 3. What is the concentration of hydroxide ions in the solution? A B C D 6 hydrogen hydrogen chloride sodium chloride sodium hydroxide 1 10 4 mol dm 3 1 10 7 mol dm 3 1 10 8 mol dm 3 1 10 14 mol dm 3 The kinetics of the reaction of nitrogen(II) oxide with hydrogen were investigated. 2NO + 2H2 2H2O + N2 The following data were obtained. [NO] mol dm 3 [H2] mol dm 3 Relative rate of reaction 1.0 3.0 3.0 1.0 1.0 2.0 1 9 18 What is the rate equation for the reaction? A B C D A2C1W7 rate = k[NO][H2] rate = k[NO]2[H2] rate = k[NO]2[H2]2 rate = k[NO][H2]2 2738 3 [Turn over 7 Which one of the following is used for the rate constant of a third order reaction? A B C D 8 For which one of the following titrations is there no suitable indicator? A B C D 9 s 1 mol dm 3 s 1 mol2 dm 6 s 1 mol 2 dm6 s 1 Na2CO3(aq) against H2SO4(aq) NH3(aq) against CH3COOH(aq) Ca(OH)2(aq) against HCl(aq) I2(aq) against Na2S2O3(aq) The conjugate base of methanol is A B C D OH CH3O CH3+ CH3O+ 10 For which one of the following chlorides is it not possible to construct a Born-Haber cycle? A B C D A2C1W7 AgCl HCl RbCl MgCl2 2738 4 [Turn over BLANK PAGE (Section B starts overleaf) A2C1W7 2738 5 [Turn over Section B Examiner Only Marks Remark Answer all six questions in the spaces provided. 11 When chlorine gas is passed into aqueous sodium thiosulphate the products are sulphate(VI) ions, chloride ions, hydrogen ions and Na2S2O3. (a) Write a balanced ionic equation for the reaction. ______________________________________________________ [2] (b) State the change in oxidation numbers for chlorine and sulphur in this reaction. _________________________________________________________ ______________________________________________________ [2] (c) State the industrial use of the reaction between chlorine and sodium thiosulphate. ______________________________________________________ [1] A2C1W7 2738 6 [Turn over 12 The diagram shows how to distinguish between propanal and propanone. Examiner Only Marks Tollen s reagent + propanal or propanone Remark water heat (a) State the metal ion present in Tollen s reagent. ______________________________________________________ [1] (b) State the functional group present in both propanal and propanone. ______________________________________________________ [1] (c) Explain why hot water is used. _________________________________________________________ ______________________________________________________ [1] (d) State what is observed in separate experiments with propanal and propanone. Propanal _________________________________________________ ______________________________________________________ [1] Propanone _______________________________________________ ______________________________________________________ [1] A2C1W7 2738 7 [Turn over 13 Poisonous carbon monoxide may be detected and estimated by several methods. Examiner Only Marks Remark (a) A sample of gas is believed to be pure carbon monoxide. How could you prove, using combustion, that the gas is carbon monoxide? _________________________________________________________ ______________________________________________________ [2] (b) Carbon monoxide can be detected using a piece of filter paper soaked in palladium chloride. The paper blackens due to the formation of palladium by a redox reaction. CO + PdCl2 + H2O CO2 + 2HCl + Pd (i) Explain the meaning of the term redox. _____________________________________________________ ___________________________________________________ [1] (ii) Calculate the number of milligrams of palladium formed if 360 dm3 of air containing 0.001% by volume of carbon monoxide are in contact with a piece of filter paper containing palladium chloride. Assume the reaction takes place at 20 C and a pressure of one atmosphere and the palladium chloride is in excess. _____________________________________________________ _____________________________________________________ _____________________________________________________ ___________________________________________________ [3] A2C1W7 2738 8 [Turn over (c) The traditional quantitative method of analysis is to pass air containing carbon monoxide over iodine pentoxide. Any carbon dioxide present in the air is removed beforehand. Examiner Only Marks Remark 5CO(g) + I2O5(s) 5CO2(g) + I2(s) The carbon dioxide formed is passed through baryta water (barium hydroxide solution) to form a precipitate of barium carbonate, BaCO3, which is filtered, washed and weighed. (i) Draw a diagram of the labelled apparatus which could be used to pass air over iodine pentoxide and then immediately pass the air through baryta water. [2] (ii) Write the equation for the reaction of barium hydroxide with carbon dioxide. ___________________________________________________ [1] (iii) Calculate the percentage of carbon monoxide, by volume, in 30 dm3 of air if 0.493 g of barium carbonate are formed. ______________________________________________________ ______________________________________________________ ___________________________________________________ [3] A2C1W7 2738 9 [Turn over (d) Electrochemical methods may be used to detect carbon monoxide. The reactions occurring in one detector are: Examiner Only Marks Remark At the positive electrode CO + H2O CO2 + 2H+ + 2e E = 0.10 V At the negative electrode O2 + 4H+ + 4e 2H2O E = +1.23 V (i) Write the overall redox equation for the cell. ___________________________________________________ [1] (ii) Calculate the emf of the cell formed. ___________________________________________________ [1] A2C1W7 2738 10 [Turn over 14 Fats are naturally occurring esters of long chain fatty acids and glycerol. The fatty acids may be saturated or unsaturated. Examiner Only Marks Remark (a) Fats may be produced by the equilibrium reaction between a fatty acid and glycerol. CH2OH | CHOH + 3RCOOH | CH2OH CH2O.OCR | CHO.OCR | CH2O.OCR + 3H2O (i) Name a catalyst that can be used in this reaction. ___________________________________________________ [1] (ii) State the systematic name for glycerol. ___________________________________________________ [2] (iii) The fat may alternatively be produced by the reaction of an acyl chloride with glycerol. Write the equation for the reaction and explain why an equilibrium is not produced. ___________________________________________________ [2] A2C1W7 2738 11 [Turn over (b) The most important unsaturated fatty acids have 18 carbon atoms with one or more double bonds. Oleic acid contains one double bond and linolenic acid contains three. Examiner Only Marks Remark (i) Draw the structure of cis oleic acid. [1] (ii) In linolenic acid, CH3CH2CHCHCH2CHCHCH2CHCH(CH2)7COOH, each double bond has a cis structure. Draw the structure of the acid. [1] (iii) Write the formula of stearic acid which is saturated and also contains 18 carbon atoms. ___________________________________________________ [1] A2C1W7 2738 12 [Turn over (c) (i) A comparison between the degree of unsaturation of oils and fats can be made using bromine water. Samples of lard and olive oil can be dissolved in a solvent and treated with bromine water. Explain how you would carry this out naming an appropriate solvent and state the results expected. Examiner Only Marks Remark ______________________________________________________ ______________________________________________________ ______________________________________________________ ______________________________________________________ ______________________________________________________ ______________________________________________________ ___________________________________________________ [3] Quality of written communication [2] (ii) The degree of unsaturation of a fat or oil may be measured using the iodine value. Define the term iodine value. ______________________________________________________ ___________________________________________________ [2] (iii) Triolein has a relative molecular mass of 884 and one molecule contains three double bonds. Using your definition calculate the iodine value of triolein. _____________________________________________________ _____________________________________________________ _____________________________________________________ __________________________________________________ [3] A2C1W7 2738 13 [Turn over 15 Chlorination of ethanoic acid produces three substituted chloroethanoic acids. The first step is: Examiner Only Marks Remark Cl2 + CH3COOH CH2ClCOOH + HCl Data on the acids is shown below. Boiling point/ C pKa Dissociation constant/ mol dm 3 LD50 of sodium salt Monochloroethanoic acid 189 2.82 1.5 10 3 0.5 Dichloroethanoic acid 194 5.1 10 2 2.8 Trichloroethanoic acid 196 2.0 10 1 3.3 Acid 0.70 (a) (i) Suggest why all three acids have a greater boiling point than that of ethanoic acid which is 118 C. ______________________________________________________ ___________________________________________________ [2] (ii) Calculate the pKa of dichloroethanoic acid. ______________________________________________________ ___________________________________________________ [1] (b) Trichloroethanoic acid is almost as strong as mineral acids such as hydrochloric acid. Calculate the pH of a 0.1 mol dm 3 solution of trichloroethanoic acid. _________________________________________________________ _________________________________________________________ ______________________________________________________ [3] A2C1W7 2738 14 [Turn over (c) The sodium salt of monochloroethanoic acid together with monochloroethanoic acid can act as a buffer solution. Examiner Only Marks Remark (i) Explain the term buffer. ______________________________________________________ ___________________________________________________ [2] (ii) Use equations to explain how this buffer mixture is able to remove both H+ and OH ions if an acid or alkali is added. _____________________________________________________ _____________________________________________________ __________________________________________________ [2] (iii) Explain why a mixture of sulphuric acid and sodium sulphate cannot act as a buffer. ______________________________________________________ ___________________________________________________ [1] (d) The LD50 is an indication of the poisonous nature of a compound. It is the number of milligrams per kg of body mass that will kill a person. Calculate the number of moles of sodium monochloroethanoate that will kill a man weighing 90 kg. _________________________________________________________ _________________________________________________________ ______________________________________________________ [3] A2C1W7 2738 15 [Turn over 16 Aluminium dissolves slowly in cold dilute hydrochloric acid but rapidly in hot concentrated hydrochloric acid. Dilute sulphuric acid has little effect but hot concentrated sulphuric acid dissolves the aluminium in a similar way to copper. Examiner Only Marks Remark (a) The aqueous solution of aluminium in hydrochloric acid deposits crystals of Al2Cl6.12H2O. On heating, the hydrate decomposes, giving off fumes of hydrogen chloride and leaving aluminium oxide. (i) Write the equation for the decomposition of the hydrate. ___________________________________________________ [1] (ii) Explain how you could confirm that hydrogen chloride was given off. ______________________________________________________ ___________________________________________________ [2] (b) Aluminium chloride can also be obtained by passing dry chlorine over aluminium metal. (i) Write the equation for the formation of aluminium chloride. ___________________________________________________ [1] (ii) Explain why the chlorine must be dry. ___________________________________________________ [1] (iii) Aluminium chloride is believed to exist as a dimeric structure. Complete the diagram below; show the outer electrons and draw the two coordinate bonds, which hold the AlCl3 molecules together. Cl Cl Cl Al Cl Al Cl Cl [3] (iv) State one property, which shows that aluminium chloride is covalent rather than ionic. ___________________________________________________ [1] A2C1W7 2738 16 [Turn over (c) Aluminium sulphate is formed when either aluminium oxide or aluminium is dissolved in sulphuric acid. Examiner Only Marks Remark (i) Write the equation for the reaction of aluminium with hot, concentrated sulphuric acid. ___________________________________________________ [1] (ii) Aluminium oxide also dissolves in alkalis. Write the equation for its reaction with sodium hydroxide and state the name given to an oxide, which dissolves in acids and alkalis. ______________________________________________________ ___________________________________________________ [2] (iii) Explain why a solution of aluminium sulphate is acidic. ______________________________________________________ ___________________________________________________ [2] THIS IS THE END OF THE QUESTION PAPER A2C1W7 2738 17 [Turn over S 6/06 2300 9-046-1 [Turn over

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Additional Info : Gce Chemistry January 2007 Assessment Unit A2 1 Module 4: Further Organic, Physical and Inorganic Chemistry
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