(a)(i) What is meant by cracking of petroleum fractions? (ii) Write an equation for the laboratory preparation of ethene from ethanol. (iii) Give one chemical test to distinguish between ethane and ethene.
(b)(i) Name the class of carbohydrates to which starch and cellulose belong. (ii) What process is used for isolating ethanol from the other products of fermentation of sugar? (iii) Name the organic product of the reaction between ethanol and sodium (iv). Write the structural formula of 2-chloroethanol.
(c) State the reason why: (i) benzene produces more soot than ethene on burning in excess air; (ii) ethanoic acid has a higher boiling point than methanoic acid; (iii) sodium chloride is used during the manufacture of soap. (d) Give one use of: (i) ethyne (ii) coal (iii) carbon black
Explanation
(a)(i) Cracking is the conservation of surplus supplies of less desirable fraction such as kerosine and gas oil into petrol (ii) C\(_2\)H\(_5\)OH C\(_2\)H\(_4\)
(iii) When ethane and ethene are separately passed through water (a)(i) polysaccharide (ii) Fractional distillation (iii) sodium ethoxide (iv) 2-chloro ethanol
(c)(i) Benzene produces more soot than ethene due to the high carbon of the former (ii) Because of higher molecular weight and higher carbon content in ethanoic acid than methanoic acid (iii) The sodium chloride used during the manufacture of soap is to decrease the solubility of the soap so that it separates out as hard cake (d)(i) ethyne - in synthesis to neoprene rubber (ii) coal - is used mainly as a fuel (iii) carbon black - used in manufacturing tyre
