(a)(i) Describe briefly the industrial preparation of ammonia.
(ii) Write a balanced equation for the reaction in (a)(i).
(iii) State one way of increasing the yield of ammonia in 4(a)(i).
(iv) State two uses of ammonia.
(b) Describe briefly, one chemical test for each of the following gases in the laboratory: (i) hydrogen; (ii) carbon (IV) oxide; (iii) oxygen.
(c)(i) State the composition of water gas.
(ii) List two uses of water gas.
(d) Describe briefly a simple experiment to determine the type of hardness in a sample of water.
Explanation
(a) Industrial preparation of ammonia (NH\(_{3(g)}\))
(i) Dry nitrogen (N\(_{2(g)}\)) mixed with dry hydrogen (H\(_{2(g)}\)) in the volume proportion of 1 : 3 over a pressure of 200 — 500 atm at temperature of 450°C — 500°C. Finely divided iron used as catalyst.
(ii) N\(_{7(g)}\) 3H\(_{2(g)}\) 2NH\(_{3(g)}\) Balanced equation of the reaction written above.
(iii) Way of increasing the yield of ammonia (NH\(_{3(g)}\)) is continuous removal of ammonia as it is formed or liquefying of the ammonia gas at a low temperature or high pressure.
(iv) Two uses of ammonia: (1) used in manufacture of fertilizers. (2) used as a precipitating agent. Other uses: Manufacture of trioxonitrate (v) acid; manufacture of sodium trioxocarbonate.
(iv) textiles, pesticides, used in detergent/cleasing agent, manufacture of plastics, laundry works, pharmaceuticals as a refrigerant, softening temperarily hard water, removal of insect stings.
(b)(i) Chemical test for hydrogen H\(_{2(g)}\), a lighted wooden splint is brought to the tip of a test tube containing the gas. The gas gives a pop sound shows the presence of Hydrogen H\(_{2(g)}\).
(ii) CO\(_{2(g)}\), The gas bubble through limewater Ca(OH)\(_{2}\) solution. The lime water turns milky shows the presence of CO\(_{2(g)}\)
(iii) Oxygen O\(_{2(g)}\), a glowing (wooden) splint dipped into a test tube of the gas. The (wooden) splint rekindles or relights shows that O\(_{2(g)}\) is present.
(c)(i) Composition of water gas: Carbon (II) oxide (CO\(_{g}\)) and Hydrogen gas H\(_{2(g)}\)
(ii) 2 Uses of water gas:
(1) industrial manufacture of hydrogen.
(2) industrial manufacture of methanol butanol.
(3) used as fuel.
(d) A simple experiment to determine type of hardness in a sample of water. Sample of water boiled, soap added and shaken, if it forms lather easily it is temporary hardness, if it forms lather with difficultly or does not form lather easily it is permanent hardness.