9701_s12_qp_22
A paper of Chemistry, 9701
Questions:
4
Year:
2012
Paper:
2
Variant:
2
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1
The elements of the third period of the Periodic Table, sodium to sulfur, all form chlorides by direct combination. Sulfur forms a number of chlorides which are liquid at room temperature. Which other element of the third period forms a chloride which is liquid at room temperature? Name one element of the third period which burns in chlorine with a coloured fl ame. Aluminium chloride may be produced by passing a stream of chlorine over heated aluminium powder in a long hard-glass tube. State two observations you could make during this reaction. and Write a balanced equation, with state symbols, for this reaction of aluminium with chlorine. No chloride of argon has ever been produced. Suggest a reason for this. For Examiner’s Use When chlorides of the elements of the third period are added to water, some simply dissolve while others can be seen to react with the water. Complete the table below, stating how the chlorides of Na, Al, and Si behave when mixed with water. In the fi rst column use only the terms ‘dissolve’ or ‘react’. element Does the chloride dissolve or react? approximate pH of the resulting solution Na Al Si What type of reaction takes place between a chloride and water? Sulfur forms the compound S4N4 with nitrogen. The structure of S4N4 is shown below. Assume all bonds shown are single bonds. S S S S N N N N a b Determine the number of lone pairs of electrons around a nitrogen atom and a sulfur atom in S4N4. nitrogen atom sulfur atom Which bond angle, a or b, in the S4N4 molecule will be smaller? Explain your answer.
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 Alcohols such as methanol, CH3OH, are considered to be possible replacements for fossil fuels because they can be used in car engines. Defi ne, with the aid of an equation which includes state symbols, the standard enthalpy change of combustion, , for methanol at 298 K. equation defi nition Methanol may be synthesised from carbon monoxide and hydrogen. Relevant values for this reaction are given in the table below. compound CO–283 H2–286 CH3OH–726 Use these values to calculate for the synthesis of methanol, using the following equation. Include a sign in your answer. CO+ 2H2→ CH3OH= kJ mol–1 For Examiner’s Use The operating conditions for this reaction are as follows. pressure 200 atmospheres (2 × 107 Pa) temperature 600 K catalyst oxides of Cr, Cu, and Zn In the spaces below, explain how each of these conditions affects the rate of formation of methanol. pressure temperature catalyst
5. Chemical energetics  →  5.1. Enthalpy change, \(\Delta H\)
2. Atoms, molecules and stoichiometry  →  2.4. Reacting masses and volumes (of solutions and gases)
16. Hydroxy compounds  →  16.1. Alcohols
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For Examiner’s Use Food additives are substances added to food to preserve the fl avour or to improve its taste and appearance. European Union legislation requires most additives used in foods to be labelled clearly in the list of ingredients, either by name or by an ‘E number’. E296 is malic acid which occurs in unripe fruit. Malic acid has the structural formula HO2CCH2CH(OH)CO2H. Some reactions of malic acid are shown below. In the boxes below, give the structural formulae of organic compounds A to F. HO2CCH2CH(OH)CO2H concentrated H2SO4 C F A B heat with CH3CO2H / H+ heat with CH3OH / H+ cold dilute MnO4 – / H+ steam / H3PO4 D E hot concentrated MnO4 – / H+ For Examiner’s Use What type of reaction is each of the following conversions? malic acid into C C into D C into E Suggest one major commercial use of compounds such as A or B. Malic acid is chiral. Draw fully displayed formulae of the two optical isomers of malic acid. Indicate with an asterisk (*) the chiral carbon atom. Compound C also shows stereoisomerism. Draw the skeletal formulae of each of the stereoisomers of C. Label each isomer. The food additive E330 is another organic compound which occurs naturally in fruit. E330 has the following composition by mass: C, 37.5 %; H, 4.17 %; O, 58.3 %. Calculate the empirical formula of E330.
13. An introduction to AS Level organic chemistry  →  13.1. Formulas, functional groups and the naming of organic compounds
7. Equilibria  →  7.2. Brønsted–Lowry theory of acids and bases
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For Examiner’s Use Oxygen-containing organic compounds may contain a number of different functional groups including alcohol, aldehyde, carboxylic acid, ester or ketone functional groups. These functional groups may be identifi ed by their reactions with specifi c reagents. On treating compounds containing each of these functional groups with the reagents below, only fi ve reactions occur. Complete the table by placing a tick () in each box where you believe a reaction will occur. You should place no more than fi ve ticks in the table. reagent alcohol R2CHOH aldehyde RCHO carboxylic acid RCO2H ester RCO2R' ketone RCOR’ NaHCO3 Na Cr2O7 2– / H+ Compound G has the empirical formula CH2O and Mr of 90. An aqueous solution of G is neutral. There is no reaction when G is treated with NaHCO3. When 0.30 g of pure G is reacted with an excess of Na, 80 cm3 of H2, measured at room temperature and pressure, is produced. What functional group do these two reactions show to be present in G? Use the data to calculate the amount, in moles, of hydrogen atoms produced from 0.30 g of G. Hence, show that each molecule of G contains two of the functional groups you have given in . For Examiner’s Use Treatment of G with 2,4-dinitrophenylhydrazine reagent produces an orange solid. When G is warmed with Fehling’s reagent, no reaction occurs. What functional group do these reactions show to be present in G? Draw the displayed formula of this functional group. Use your answers to and to deduce the structural formula of G. Compound G can be both oxidised and reduced. When G is heated under refl ux with acidifi ed K2Cr2O7, compound H is formed. Give the structural formula of compound H. When G is reacted with NaBH4 under suitable conditions, compound J is formed. Give the structural formula of compound J.
17. Carbonyl compounds  →  17.1. Aldehydes and ketones
13. An introduction to AS Level organic chemistry  →  13.1. Formulas, functional groups and the naming of organic compounds
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