(32 marks) 8. Answer any FOUR questions.
Explain the terms " a neutral aqueous solution" and "an amphiprotic molecule". (ii) Calculate the pH of a buffer solution containing 0.2 mol of ethanoic acid (Ka = 1.8x and 0.1 mol of sodium ethanoate per dm3 .
(b) i) Define 'heat of combustion'.
(ii) Calculate the heat of formation of oxalic acid, C2H204 (s) , if its heat of combustion is - 827 kJ mol-I . The heat of combustion of carbon graphite and hydrogen are — 393 kJ mol-I and — 286 kJ mol-I respectively.
(c) (i) What products would you expect when CH3COONa is heated with soda-lime?
(ii) Illustrate the preparation of ethanol from glucose.
(iii) How would you obtain ethanal from ethyne?
(iv)How does ethene react with hydrogenchloride?
(d) (i) How would you distinguish between ethane and ethene?
(ii) A gas "X" is obtained by treating calcium carbide with water. What is gas "X" ? Write down the chemical equation.
(iii) Name the chemicals which can be obtained from coal and mention their uses. (iv) How do you obtain Gasoline from methanol?
(e) escribe the Manufacturing of sulphuric acid by Contact Process.
(f) Write the balanced equations (words and symbols) for the laboratory preparations of bromine and nitrogenoxide gases. (Any one method for each gas) State the collection methods and their respective reasons.
(g) 25 cm3 ofO. 1M sodium carbonate solution required 24 cm3 of sulphuric acid to neutralize it.
(i) Calculate the molar concentration of sulphuric acid.
(ii) What volume of water should be added to 24 cm3 of sulphuric acid so that the concentration becomes exactly O. I M ?
(hjßescribe the extraction of silver from silver glance by the cyanide process.
