(a)(i) State three characteristics of a homologous series.
(ii) Give the name and structural formula of the second member of the alkyne series.
(iii) Write an equation to represent the combustion of ethane in excess oxygen.
(b) Name the type of reaction involved in the conversion of ethanol to
(i) ethene;
(ii) ethylethanoate;
(iii) chloroethane;
(iv) ethoxide
(v) ethanoic acid
(c) Consider the following compound.
(i) Write its IUPAC name.
(ii) Give its molecular formula and empirical formula
(iii) List the products of its H H 0 reaction with saturated Na(_2)CO(_3) solution.
(iv) State with reason whether its boiling point will be higher or lower than that of the corresponding alkane.
(d) A vegetable oil X was treated with activated charcoal and then with a gas Y in the presence of a catalyst in order to manufacture
(i) Identify Y.
(ii) State the function of the activated charcoal.
(iii) What is the catalyst used?
(iv) If a sample of X is heated with concentrated sodium hydroxide solution, list the products that will be obtained.
Explanation
(a)(i) -All members of a homologous series share a general molecular formula.
-Each successive member in a series differs in its molecular formula by the addition of a – CH2 -.
-All members show similar chemical properties
-All members can usually be prepared by using the same general methods.
(ii) The second member of the alkyne is propyne with formula C(_3)H(_4).
The structure is
(iii) C(_2)H(_6) + 4(_2) -> 2CO(_2) + 4H(_2)O
(b)(i) Dehydration
(ii) Esterification
(iii) Substitution
(iv) Reduction
(v) Oxidation
(c)(i) 2 – methylpropanoic acid
(ii) Molecular formula C(_4)H(_8)O(_2) = CH(_3) CH(CH(_3)) COOH. Empirical formula = C(_2)H(_4)O
(iii) Sodium, 2 – methyl propanoate and water. (CH(_3)CH(CH(_3))COONa + H(_2)O)
(iv) The boiling point of 2 – methyl propanoic acid will be higher than that of the corresponding alkane because it is a liquid, while the corresponding alkane is a gas.
(d)(i) Y is hydrogen.
(ii) The activated charcoal is to bleach off the natural colour of the oil.
(iii) Finely divided nickel.
(iv) The product are soap and propane – 1, 2, 3 – triol.