Chemistry 1993 Waec Past Questions and Answers

Question 46 :

• WAEC 1993

(a)(i) Define the term polymerization.
(ii) List the three conditions required for the polymerization on of ethene.
(iii) State the property which is common to compounds that can be easily polymerized

(b) Write appropriate equations to show how the following can be obtained from propan-1-ol in the labouratory
(i) propene;
(ii) propylmethanoate. State the type of reaction involved in each case.

(c)(i) A compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen. Determine its molecular formula if its molar mass is 180 (H = 1, C = 12, O = 16)
(ii) Explain why ethanoic acid boils at a much higher temperature than butane even though their molar masses almost equal.

Question 47 :

• WAEC 1993

(a)(i) What is meant by the rate of a chemical reaction?
(ii) Explain in terms of the vision theory, the effect of temperature increase on reaction rate.

(b) When hydrogen peroxide is exposed to air, it decomposes
(i) Write an equation for the reaction.
(ii) Outline an experiment to illustrate that effect of a named catalyst on the rate of decomposition.
(iii) Sketch an energy profile diagram to show the effect of the catalyst on the reaction rate, given that the reaction is exothermic.
(c)(i) Explain why enthalpy data alone cannot be used to predict whether a reaction can occur spontaneously or not.