9701_w08_qp_2
A paper of Chemistry, 9701
Questions:
5
Year:
2008
Paper:
2
Variant:
0
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1
Examiner s Use Most submarines travel under water using electrical power from batteries. The German engineer Helmut Walter designed a diesel engine that could be used to propel a submarine beneath the surface of the sea. Instead of taking air from above the surface of the sea, Walter’s engine used hydrogen peroxide, H2O2, to provide oxygen for a conventional diesel engine. Hydrogen peroxide may be catalytically decomposed to give water and oxygen. What is meant by the term catalyst? Construct a balanced equation for the decomposition of H2O2. Diesel fuel may be considered to consist of the hydrocarbon C15H32 which reacts completely with oxygen according to the following equation. C15H32 + 23O2 → 15CO2 + 16H2O To which homologous series does C15H32 belong? Use the equation above and your answer to to calculate the amount, in moles, of H2O2, that will provide sufficient oxygen for the complete oxidation of one mole of C15H32. amount of H2O2 = mol For Examiner’s Use A submarine equipped with a Walter engine used 212 tonnes of diesel fuel during an underwater voyage. The submarine also carried concentrated aqueous H2O2. [1 tonne = 106g] Calculate the amount, in moles, of diesel fuel used during the underwater voyage. amount of diesel fuel = mol Use your answers to and to calculate the mass, in tonnes, of hydrogen peroxide used during the underwater voyage. mass of H2O2 = tonnes The exhaust products of the Walter engine were passed into the sea. What would happen to them?
14. Hydrocarbons  →  14.1. Alkanes
2. Atoms, molecules and stoichiometry  →  2.4. Reacting masses and volumes (of solutions and gases)
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For Examiner’s Use Ketene, C2H2O, is a member of a class of unsaturated organic compounds that is widely used in pharmaceutical research for the synthesis of organic compounds. CH2=C=O ketene Suggest values for the H-C-H and C=C=O bond angles in ketene. H-C-H …………………………………… C=C=O …………………………………… By considering the structure of the molecule, suggest why the name ketene is used. Ketene burns completely in air to form carbon dioxide and water. Write a balanced equation for this reaction. Use your equation to calculate the volume of CO2, in dm3, measured at room temperature and pressure, which will be formed when 3.5g of ketene are burned in an excess of air. Give your answer to two significant figures. volume of CO2 = dm3 For Examiner’s Use Define the term standard enthalpy change of formation. Use the data below to calculate the standard enthalpy change of formation of ketene. ∆H o/kJ mol–1 standard enthalpy change of formation of CO2 –395 standard enthalpy change of combustion of H2 –286 standard enthalpy change of combustion of CH2=C=O –1028 Ketene can be converted directly into ethanoic acid, CH3CO2H, by reaction with a compound A. Suggest the identity of A. ………………
14. Hydrocarbons  →  14.1. Alkanes
5. Chemical energetics  →  5.1. Enthalpy change, \(\Delta H\)
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For Examiner’s Use Chlorine gas is manufactured by the electrolysis of brine using a diaphragm cell. Write half-equations, including state symbols, for the reactions occurring at each of the electrodes of a diaphragm cell. anode cathode In the diaphragm cell, the anode is made of titanium and the cathode is made of steel. Suggest why steel is never used for the anode. One important product made in the diaphragm cell is formed in aqueous solution. What substance is produced in aqueous solution in the diaphragm cell? Explain, with the aid of appropriate half-equation, how this compound is formed by electrolysis. Chlorine is very reactive and will form compounds by direct combination with many elements. Describe what you would see when chlorine is passed over separate heated samples of sodium and phosphorus. In each case write an equation for the reaction. sodium phosphorus For Examiner’s Use Magnesium chloride, MgCl2, and silicon tetrachloride, SiCl4, each dissolve in or react with water. Suggest the approximate pH of the solution formed in each case. MgCl2 ………………………………… SiCl4 ………………………………… Explain, with the aid of an equation, the difference between the two values.
11. Group 17  →  11.4. The reactions of chlorine
9. The Periodic Table: chemical periodicity  →  9.2. Periodicity of chemical properties of the elements in Period 3
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For Examiner’s Use Organic chemistry is the chemistry of carbon compounds. The types of organic reactions that you have studied are listed below. addition elimination hydrolysis oxidation reduction substitution Addition and substitution reactions are further described as follows. electrophilic nucleophilic free radical Complete the table below. Fill in the central column by using only the types of reaction given in the lists above. Use both lists when appropriate. In the right hand column give the nameor formulaof the reagentyou would use to carry out the reaction given. organic reaction type of reaction reagentCH3CHO → CH3CH(OH)CN CH3CH2CH2CH3 → CH3CH2CHBrCH3 CH3CH(OH)CH3 → CH3CH=CH2 CH3CH=CH2 → CH3CH(OH)CH2OH
13. An introduction to AS Level organic chemistry  →  13.2. Characteristic organic reactions
21. Organic synthesis  →  21.1. Organic synthesis
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For Examiner’s Use An organic ester, B, has the empirical formula C2H4O. An experiment by a student in a college gave a value of 87.5 for Mr of B. What is the molecular formula of B? ………………………… In the boxes below, draw the structural formulae of four isomers of B that are esters. W X Y Z For Examiner’s Use The student hydrolysed his sample of B by heating with aqueous mineral acid and then separating the alcohol, C, that was formed. He heated the alcohol C under reflux with acidified dichromate(ions and collected the product D. A sample of D gave an orange precipitate with 2,4-dinitrophenylhydrazine reagent. A second sample of D gave no reaction with Tollens’ reagent. What group does the reaction with 2,4-dinitrophenylhydrazine reagent show to be present in D? ……………………………………… What does the result of the test with Tollens’ reagent show about D? ……………………………………… What is the structural formula of the alcohol C? Which of your esters, W, X, Y, or Z has the same structure as that of the ester B? ……………… Which, if any of your esters, W, X, Y, or Z is chiral? Explain your answer.
13. An introduction to AS Level organic chemistry  →  13.1. Formulas, functional groups and the naming of organic compounds
17. Carbonyl compounds  →  17.1. Aldehydes and ketones
18. Carboxylic acids and derivatives  →  18.2. Esters
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