(a)(i) Define polymerization. (ii) Mention two... | WAEC SSCE - Chemistry - 2009

Question 1 Report

(a)(i) Define polymerization.

(ii) Mention two types of polymerization.

(iii) Give one example of I. naturally occurring polymer, II. synthetic polymer.

(b)(i) Describe how ethyne could be prepared in the laboratory.

(ii) Write an equation for the I. polymerization of ethyne II. complete reaction of ethyne with hydrogen bromide.

(iii) Name each of the products formed in (b)(ii) II.

(c)(i) Define each of the following terms: I. pollution; Il. pollutant.

(ii) Mention three types of pollution.

(iii) Give two ways by which pollution can be prevented.

Answer

(a)(i) Polymerization

Polymerization is the chemical process by which many small molecules (monomers) combine together to form one very large molecule (a polymer).

(a)(ii) Two types of polymerization

Addition polymerization and condensation polymerization.

(a)(iii) Examples

I. Naturally occurring polymer: rubber (also starch, cellulose or protein).
II. Synthetic polymer: polythene (also polyvinyl chloride, PVC, or nylon).

(b)(i) Laboratory preparation of ethyne

Place a few lumps of calcium dicarbide (calcium carbide) in a flask and add water drop by drop. Ethyne gas is evolved rapidly and is collected over water.

\[CaC_{2(s)} + 2H_2O_{(l)} \to Ca(OH)_{2(aq)} + C_2H_{2(g)}\]

(b)(ii) Equations

I. Polymerization of ethyne (to benzene):

\[3C_2H_2 \to C_6H_6\]

II. Complete reaction of ethyne with hydrogen bromide:

\[C_2H_2 + 2HBr \to C_2H_4Br_2\]

(b)(iii) Name of the product

The product of the complete reaction with hydrogen bromide is 1,1-dibromoethane (\(CH_3CHBr_2\)).

(c)(i) Definitions

I. Pollution: the introduction of harmful substances (pollutants) into the environment, causing damage to living things and their surroundings.
II. Pollutant: the harmful substance that causes pollution.

(c)(ii) Three types of pollution

Air pollution, water pollution and land (soil) pollution. (Noise pollution is also acceptable.)

(c)(iii) Two ways of preventing pollution

Proper treatment and safe disposal of industrial and domestic wastes (and recycling).
Fitting factories and vehicles with filters/catalytic converters to reduce harmful emissions, and afforestation.

Read lesson note on Organic Compounds (JAMB)

Answer Details