9701_w05_qp_2
A paper of Chemistry, 9701
Questions:
5
Year:
2005
Paper:
2
Variant:
0
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1
The first six ionisation energies of an element X are given below. Define the term first ionisation energy. Write an equation, with state symbols, for the second ionisation energy of element X. Use the data given above to deduce in which Group of the Periodic Table element X is placed. Explain your answer. Group explanation The first ionisation energies (I.E.) for the elements of Group IV are given below. Explain the trend shown by these values in terms of the atomic structure of the elements. Examiner s Use first second third fourth fifth sixth ionisation energy / kJ mol–1 element C Si Ge Sn Pb 1st I.E. / kJ mol–1
1. Atomic structure  →  1.4. Ionisation energy
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2
Carbon disulphide, CS2, is a volatile, stinking liquid which is used to manufacture viscose rayon and cellophane. The carbon atom is in the centre of the CS2 molecule. Draw a ‘dot-and-cross’ diagram of the carbon disulphide molecule. Show outer electrons only. Suggest the shape of the molecule and give its bond angle. shape bond angle Explain the term standard enthalpy change of formation, Hf . Calculate the standard enthalpy change of formation of CS2 from the following data. standard enthalpy change of formation of SO2 = –298 kJ mol–1 standard enthalpy change of formation of CO2 = –395 kJ mol–1 standard enthalpy change of combustion of CS2 = –1110 kJ mol–1 For Examiner’s Use Carbon disulphide reacts with nitrogen monoxide, NO, to form a yellow solid and two colourless gases which are produced in a 1:1 molar ratio. Deduce the identity of each gas and write a balanced equation for the reaction. gases and equation [T For Examiner’s Use
5. Chemical energetics  →  5.1. Enthalpy change, \(\Delta H\)
2. Atoms, molecules and stoichiometry  →  2.4. Reacting masses and volumes (of solutions and gases)
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3
Nitrogen, which makes up about 80% of the Earth’s atmosphere, is very unreactive. Explain the lack of reactivity of nitrogen. Nitrogen does, however, undergo some reactions. Write an equation for one reaction of nitrogen, stating the conditions under which it occurs. equation conditions Suggest why nitrogen does react in the example you have chosen. Ammonium nitrate, NH4NO3, is a commercially important compound of nitrogen. State one large-scale use of ammonium nitrate. What are the environmental consequences of the uncontrolled use of ammonium nitrate? For Examiner’s Use When solid ammonium nitrate is heated with solid sodium hydroxide in a test-tube, three products are formed. A colourless alkaline gas, Y, is given off, and a colourless liquid can be seen on the cooler parts of the test-tube. A white solid remains in the tube. Identify gas Y. Write an equation, with state symbols, for the reaction of ammonium nitrate with sodium hydroxide. In order to produce gas Y in a pure state in the laboratory, it must be passed through a drying agent. Why is concentrated sulphuric acid not suitable for drying gas Y? [T For Examiner’s Use
12. Nitrogen and sulfur  →  12.1. Nitrogen and sulfur
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4
Alcohols are widely used as solvents and in the manufacture of esters. Butan-1-ol, C4H10O, is an example of a primary alcohol. What is meant by the term primary alcohol? There are three more alcohols with molecular formula C4H10O that are structural isomers of butan-1-ol. Complete the table below by drawing displayed formulae of each of these three compounds. For each isomer, state whether it is a primary, secondary, or tertiary alcohol. For Examiner’s Use H H H C C H H C H H C OH H H primary butan-1-ol isomer 2 isomer 3 isomer 4 Butan-1-ol can be oxidised to a carboxylic acid by heating with an acidified solution of potassium dichromate(. What colour change would be seen during this reaction? from to State which of the isomers you have drawn in could also be oxidised to form a carboxylic acid. [T For Examiner’s Use
16. Hydroxy compounds  →  16.1. Alcohols
17. Carbonyl compounds  →  17.1. Aldehydes and ketones
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5
Compound Z, an organic compound with three functional groups, has the molecular formula C4H6O2. The functional groups can be confirmed by the following tests. Test for the first functional group. Z decolourises aqueous bromine. What functional group is shown to be present in Z by this test? Tests for the second functional group. Z reacts with sodium to give hydrogen and a solid compound of formula C4H5O2Na. When Z is heated with ethanoic acid and a few drops of concentrated sulphuric acid, a sweet smelling liquid of molecular formula C6H8O3 is formed. What functional group is shown to be present in Z by these tests? Tests for the third functional group. A few drops of Z form a yellow/orange precipitate when added to 2,4-dinitrophenylhydrazine reagent. When a few drops of Z are warmed with Tollens’ reagent, a silver mirror is formed. What functional group is shown to be present in Z by these tests? Z does not show cis-trans isomerism. Draw the displayed formula of Z. For Examiner’s Use For Examiner’s Use In parts and you may use R– to represent the part of the molecule that does not react. What is the organic compound formed by the reactions of Z in each of the tests in ? with sodium with ethanoic acid Draw the structure of the organic compound formed by Z in each of the tests in . with Tollens’ reagent with 2,4-dinitrophenylhydrazine, But-2-enoic acid is an isomer of Z which shows cis-trans isomerism. Draw a displayed formula of the cis isomer of this acid. NHNH2 NO2 NO2
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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