Chem Alkanes and Alkenes Ws

Secondary 4 Express Pure Chemistry – Alkanes and Alkenes Page 1 of 9 Name : _______________________() Class: _________ Date: _______ 1 Which compound undergoes an addition reaction with bromine? A C2H4 B C 2H6 C C 2H5OH D CH 3CO2H 2 What feature would show that a compound must be an alkene? A if it only contains carbon and hydrogen B if it reacts with bromine C if it is a hydrocarbon with a C=C bond D if it burns in air with a smoky flame 3 A 10 cm3 sample of a gaseous hydrocarbon was completely burnt in oxygen. The total volume of the products was 80 cm3. Which equation represents the combustion of the hydrocarbon? A CH4(g) + 2O2(g)  CO2(g) + 2H2O(g) B 2C2H6(g) + 7O2(g)  4CO2(g) + 6H2O C C3H8(g) + 5O2(g)  3CO2(g) + 4H2O D C4H8(g) + 6O2(g)  4CO2(g) + 4H2O(g) 4 Which compound reacts with steam to produce an alcohol? A butene B ethanoic acid C methane D propane 5 Nonane, the ninth member of alkanes, is present in petrol. What products are formed when nonane is completely burnt in air? A carbon dioxide and hydrogen B carbon monoxide and water C carbon dioxide and water D carbon dioxide, carbon monoxide and water

Secondary 4 Express Pure Chemistry – Alkanes and Alkenes Page 2 of 9 6 Which structural formula represents an unsaturated hydrocarbon? A B C D H H H O H H Cl H C C C C C H C C C O C C H H H H H H H H H H H 7 Which one of these equations does not shown an addition reaction? A CH3Cl + Cl2  CH2Cl2 + HCl B C3H6 + Br2  C3H6Br2 C C4H8 + H2O  C4H9OH D nC2H4  -[-CH2-CH2-]-n 8 What feature would show that a compound must be an alkane? A if it burns in air B if it only contains carbon and hydrogen C if it reacts with chlorine D if it has the general formula CnH(2n + 2) 9 The structures of two compounds are shown below. H H C H H H H H H and H H H H C C C C C H H C C C C H H H H H H H H H H What must be the same for the two compounds? A the melting point B the structural formula C the boiling point D the percentage composition by mass

Secondary 4 Express Pure Chemistry – Alkanes and Alkenes Page 3 of 9 10 Decane is an alkane containing ten carbon atoms per molecule. What is its molecular formula? A C10H18 B C10H20 C C10H22 D C10H24 11 The diagrams show the structures of three compounds. H H H H H H H C C H H C C H H C C Cl Cl H Cl Cl H Cl 1 2 3 Which compounds could be the products of the substitution reaction between ethane with chlorine? A 1 only B 2 only C 1 and 3 only D 1, 2 and 3 12 Compounds X and Y are two different alkenes. Which statement about X and Y is not correct? A They both undergo addition reactions. B They have the same empirical formula. C They both contain carbon and hydrogen only. D They have the same boiling point.

Secondary 4 Express Pure Chemistry – Alkanes and Alkenes Page 4 of 9 Section B: Structured Questions 1 The table shows some data about the first six members of the alkane homologous series. alkane number of carbon atoms in one molecule X melting point / oC boiling point / oC heat energy released by complete combustion of 1 mole of alkane / kJ Y methane 1 -182 -162 880 ethane 2 -183 -89 1540 propane 3 -188 -42 2200 butane 4 -138 0 2880 pentane 5 -130 36 hexane 6 -95 69 4140 (a) Plot a graph of Y against X on the graph grid below. [3] (b) Use the graph to estimate the value of Y for pentane. Write your answer in the table. [2]

Secondary 4 Express Pure Chemistry – Alkanes and Alkenes Page 5 of 9 (c) Calculate the energy released by one gram of methane. ......................................................................................................................................... ......................................................................................................................................... [1] (d) Give the molecular formula of an alkane which is a liquid at room temperature and and pressure (25oC and 1 atmosphere). ......................................................................................................................................... [1] (e) Butane has two isomers. Draw the structural formula of both isomers. [2] (f) State the difference in the molecular formula of two successive members of a homologous series. .................................................................................................................................... [1] 2 Cracking is used to break big hydrocarbon molecules into smaller ones. (a) (i) State the conditions required for cracking. .................................................................................................................................... [1] (ii) State and explain one advantage to motor vehicles of cracking. ....................................................................................................................................... ....................................................................................................................................... ..................................................................................................................................[2]

Secondary 4 Express Pure Chemistry – Alkanes and Alkenes Page 6 of 9 (b) A hydrocarbon, C14H30, is cracked to give two products. One of the products is propane. (i) What is the molecular formula of the other product? ....................................................................................................................................... (ii) Describe a chemical test to show that the other product is unsaturated. test: ............................................