9701_s12_qp_21
A paper of Chemistry, 9701
Questions:
5
Year:
2012
Paper:
2
Variant:
1
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Oxides are compounds which usually contain oxygen combined with one other element. Oxides are classifi ed as follows. acidic alkaline amphoteric basic Using these terms only, complete the table to describe the oxides of the elements of the third period of the Periodic Table sodium to sulfur. Na2O MgO Al 2O3 SiO2 P4O10 SO2 Cl 2O7 acidic Give the names of two elements from sodium to chlorine which form more than one oxide. and Sodium reacts with water. Describe, as fully as you can, what you would see when a piece of sodium is reacted with water. Write an equation for the reaction of sodium with water. For Examiner’s Use Sulfur dioxide is present in small, but signifi cant, amounts in the Earth’s atmosphere. State one way by which sulfur dioxide enters the atmosphere. Give the formula of another sulfur compound which is formed in the atmosphere from sulfur dioxide. What are the environmental consequences of the compound you have identifi ed in ? Sulfur dioxide is used as a food preservative. What property of sulfur dioxide enables it to act in this way? Another sulfur compound which is present in the Earth’s atmosphere is carbonyl sulfi de, OCS. The sequence of atoms in the molecule is oxygen-carbon-sulfur and the molecule is not cyclic. Draw a ‘dot-and-cross’ diagram of the OCS molecule. Show outer electrons only. Suggest a value for the O – C – S bond angle.
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 Ammonium sulfate, (NH4)2SO4, is widely used as a fertiliser. In order to determine its percentage purity, a sample of ammonium sulfate fertiliser was analysed by reacting a known amount with an excess of NaOHand then titrating the unreacted NaOH with dilute HCl. Ammonium sulfate reacts with NaOH in a 1 : 2 ratio. Complete and balance the equation for this reaction. (NH4)2SO4 + 2NaOH → NH3 + + A 5.00 g sample of a fertiliser containing (NH4)2SO4 was warmed with 50.0 cm3 (an excess) of 2.00 mol dm–3 NaOH. When all of the ammonia had been driven off, the solution was cooled. The remaining NaOH was then titrated with 1.00 mol dm–3 HCl and 31.2 cm3 were required for neutralisation. Write a balanced equation for the reaction between NaOH and HCl. Calculate the amount, in moles, of HCl in 31.2 cm3 of 1.00 mol dm–3 HCl. Calculate the amount, in moles, of NaOH in 50.0 cm3 of 2.00 mol dm–3 NaOH. Use your answers to , and to calculate the amount, in moles, of NaOH used up in the reaction with (NH4)2SO4. For Examiner’s Use Use your answer to and the equation in to calculate the amount, in moles, of (NH4)2SO4 that reacted with NaOH. Use your answer to to calculate the mass of (NH4)2SO4 that reacted with NaOH. Hence, calculate the percentage purity of the ammonium sulfate fertiliser.
12. Nitrogen and sulfur  →  12.1. Nitrogen and sulfur
11. Group 17  →  11.4. The reactions of chlorine
2. Atoms, molecules and stoichiometry  →  2.4. Reacting masses and volumes (of solutions and gases)
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For Examiner’s Use Methanol, CH3OH, is considered to be a possible alternative to fossil fuels, particularly for use in vehicles. Methanol can be produced from fossil fuels and from agricultural waste. It can also be synthesised from carbon dioxide and hydrogen. Defi ne, with the aid of an equation which includes state symbols, the standard enthalpy change of formation of carbon dioxide. equation defi nition Relevant values for the reaction that synthesises methanol are given in the table. compound CO2–394 CH3OH–201 H2O–242 Use these values to calculate for this synthesis of methanol. Include a sign in your answer. CO2+ 3H2CH3OH+ H2O= kJ mol–1 Suggest one possible environmental advantage of this reaction. Explain your answer. For Examiner’s Use The synthesis of methanol is carried out at about 500 K with a pressure of between 40 and 100 atmospheres (between 4 × 106 Pa and 10 × 107 Pa) and using a catalyst. The use of such conditions will affect both the rate of reaction and the equilibrium yield. In the spaces below, explain the effects of higher temperature, higher pressure, and the use of a catalyst on the equilibrium yield of methanol. higher temperature effect explanation higher pressure effect explanation use of catalyst effect explanation
2. Atoms, molecules and stoichiometry  →  2.4. Reacting masses and volumes (of solutions and gases)
5. Chemical energetics  →  5.1. Enthalpy change, \(\Delta H\)
14. Hydrocarbons  →  14.1. Alkanes
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For Examiner’s Use One method of preparing ethene in a school or college laboratory is from ethanol by using the apparatus shown below. mineral wool and ethanol pumice water ethene strong heat Write a balanced equation for this reaction. What type of reaction is this? Give the chemical name of a reagent other than pumice that could be used to carry out this reaction. It is not necessary to use the same apparatus. Ethene is bubbled into two separate test-tubes, one containing aqueous hydrogen bromide and the other containing cold, dilute acidifi ed potassium manganate(. In each case, describe any colour changes you would see and give the structural formula of the organic product. aqueous hydrogen bromide cold, dilute acidifi ed potassium manganate(colour at start colour after reaction structural formula of organic product For Examiner’s Use Cyclohexene has the following structural formula. What is the molecular formula of cyclohexene? Draw the structural formula of the compound formed when cyclohexene is reacted with bromine. State as fully as you can what type of reaction this is. Draw the structural formula of the compound formed when cyclohexene is reacted with hot concentrated acidifi ed potassium manganate(.
14. Hydrocarbons  →  14.2. Alkenes
13. An introduction to AS Level organic chemistry  →  13.1. Formulas, functional groups and the naming of organic compounds
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For Examiner’s Use Organic compounds which contain oxygen may contain alcohol, aldehyde, carboxylic acid, ester or ketone functional groups. The functional groups may be identifi ed by their reactions with specifi c reagents. Compound X has the empirical formula CH2O and Mr of 90. There is no reaction when X is treated with NaHCO3. What functional group does this test show to be not present in X? When 0.600 g of X is reacted with an excess of Na, 160 cm3 of H2, measured at room temperature and pressure, is produced. What functional group does this reaction show to be present in X? Use the data to calculate the amount, in moles, of hydrogen atoms produced from 0.600 g of X. Hence, show that each molecule of X contains two of the functional groups you have given in . For Examiner’s Use When X is warmed with Fehling’s reagent, a brick red precipitate is formed. Treatment of X with 2,4-dinitrophenylhydrazine reagent produces an orange solid. What functional group do these reactions show to be present in X? Draw the displayed formula of this functional group. Use your answers to , and to deduce the structural formula of X. What is the structural formula of the organic product of the reaction of X with Fehling’s reagent? Compound X can be both oxidised and reduced. Give the structural formula of the compound formed when X is reacted with NaBH4 under suitable conditions. Give the structural formula of the compound formed when X is heated under refl ux with acidifi ed K2Cr2O7.
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
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