Chemistry Past Questions and Answers

(a) State the main ore of tin.
(b) Write an equation for the reaction involved in the smelting of purified tin ore
(c) List two alloys of tin

(a) Name the crystalline allotrope of sulphur that is stable at room temperature.
(b)(i) Give one example of a fuel that contains significant amount of sulphur as an impurity.
(ii) State one environmental disadvantage of using a fuel that has high sulphur content

(a) Give the electrolyte of a named secondary electrochemical cell.
(b) Consider the cell represented as shown below: \(Cu_{(s)}Cu^{2+}_{(aq)}/Zn^{2+}_{(aq)}/Zn{(s)}\)
(i) What does the vertical double stroke represent?
(ii) Which of the metals forms the cathode?
(iii) Name the electrode to which each half-cell should be coupled if the oxidation potential of the half-cells are to be determined.

Magnesium ribbon reacts with dilute hydrochloric acid at room temperature.
(a) State three ways by which the reaction can be made to proceed faster
(b) Write an equation for the reaction.

(a) Give one example of naturally-occurring acids
(b) If 0.5 mole of a mono-alkanoic acid weighs 44g, determine the molecular formula and the name of the acid. (H = 1, C = 12, O = 16)