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24. (a) How is ammonia gas prepared, and what is the residue from its preparation ?

(6) How much ammonium chloride must be used to obtain 291 grams ammonia gas?

25. How is ammonia tested for ?
27. (a) How is ammonium nitrate prepared ?

(6) How much ammonium nitrate can be got from 327 grams of nitric acid ?

28. How much nitrous oxide can be obtained from 437 grams of ammonium nitrate ?

29. How can nitrous oxide be distinguished from oxygen ?

30. If 7 grams of copper be acted on with nitric acid, how much nitric oxide will be obtained, and how much copper nitrate will remain ?

31. Mention some of the properties of nitric oxide.

32. (a) How is carbon dioxide prepared from marble ?

(6) How much hydrochloric acid will be needed exactly to decompose a kilogram of marble?

33. What reaction takes place when carbon dioxide and lime-water are brought together? Give the equation.

34. (a) How is carbon monoxide prepared from formic acid, and from oxalic acid ?

(6) How much carbon monoxide should be obtained from 12 grams oxalic acid ?

35. What happens when a mixture of carbon monoxide and dioxide is shaken up with caustic soda?

36. (a) Give the equation for the preparation of chlorine from common salt, manganese dioxide, and sulphuric acid ?

(6) What is the action of hydrochloric acid on manganese dioxide ?

(c) How much chlorine can be got by heating 560 grams manganese dioxide with salt and sulphuric acid ?

(d) How much can be got by heating the same quantity with hydrochloric acid ?

37. (a) Mention the chief properties of chlorine. (6) How does chlorine act as a bleaching agent ?

38. How much common salt is needed to prepare 109 kilograms of hydrochloric acid ?

39. (a) What is meant by “neutralizing” an acid solution ?

(6) What is meant by the terms “ acids," “ bases,” and “ salts”?

40. (a) Give the equation for the preparation of bleaching powder from lime and chlorine.

(6) How much chlorine is needed to convert 5 tons of slaked lime into bleaching powder ?

41. (c) What happens when each of the following acids is brought in contact with calcium hypochlorite, sulphuric, nitric and hydrochloric ?

(6) How can a solution of hypochlorous acid be distinguished from a solution of chlorine ?

42. (a) Give the equation for the preparation of iodine from potassium iodide.

(6) Thirty-seven grams of iodine were obtained; how much potassium iodide was used ?

43. What is the best test for free iodine ? 44. (a) How is sodium iodide prepared ?

(6) How much sodium iodide can be got from 20 grams of iodine ?

45. How much bromine can be got from 85 grams potassium bromide ?

46. How much sodium, bromate and bromide, should be obtained by dissolving 97 grams bromine in caustic soda?

47. (a) How is hydrofluoric acid prepared ?

(6) What is its action upon glass, and how may it be used to etch glass?

48. (a) What is the action of strong sulphuric acid upon copper?

(6) How much sulphuric acid and copper must be used to obtain a kilogram of sulphur dioxide ?

(c) What is the action of sulphur dioxide upon nitric acid, and upon potassium chromate solution ?

50. (a) Describe in detail how sulphuretted hydrogen gas is prepared.

(6) How much ferrous sulphide must be used to obtain 42 grams of the gas ?

51. (a) How does sulphuretted hydrogen serve to divide the metals into groups ?

(6) How could you separate by means of sulphuretted hydrogen a solution containing copper, iron, and sodium ?

52. How is sodium hydrate prepared ?

54. (a) What is meant by the terms “ oxidizing" and “reducing" fames ?

(6) How is each obtained, and for what is each used?

55. (a) How would you distinguish, by means of the blow-pipe, salts of the following metals-copper, cobalt, lead, zinc, antimony, aluminium, chromium, and strontium ?

(6) What happens when mercuric chloride is heated on charcoal along with sodium bi-carbonate in the blow-pipe flame?

56. Name the substance which produces each of the following reactions :

(a) Bead brittle, soluble in nitric acid, sulphide black.

(6) No metallic bead, but incrustation of oxide on charcoal (brown).

(c) Bead malleable, soluble in nitric acid ; solution gives with sulphuric acid a white precipitate.

(d) No metallic bead, after heating; moistening with cobalt chloride and re-heating gives a pink residue.

(e) Red head, soluble in nitric acid; solution becomes bright blue on adding ammonia: borax bead blue.

(8) No metallic bead: borax bead amethyst coloured in reducing flame.

57. (a) How may a Bunsen lamp flame be substituted for the flames obtained by the mouth blow-pipe ?

(6) Which is the hottest part of the Bunsen lamp flame, and which part has most reducing power?

(c) How are metallic films and metallic beads obtained by Bunsen's flame reactions ?

58. How can arsenic, mercury, thallium, cadmium,

a

gold and platinum be distinguished by Bunsen's flame reactions ?

59. Give Bunsen's reactions for zinc, mercury, bismuth, lead, copper, and iron.

60. Give Bunsen's tests for phosphorus and sulphur, and state the reactions involved in each.

61. Six substances gave the following reactions when examined by means of Table A. Name each substance.

(a) Water evolved on heating (reaction acid). Substance dissolved in water, and on adding HCl a gas was evolved smelling of burning sulphur. None of the group reagents gave a precipitate. Flame coloration, yellow.

(6) Nitrogen tetroxide evolved on heating. Substance dissolved in water, and gave a white precipitate with hydrochloric acid, soluble in hot water.

(c) Oxygen evolved on heating. Substance insoluble in water, but dissolved by heating with hydrochloric acid with evolution of chlorine. No precipitate with HCl, or with HCl + H2S, but on adding (NH4)HO + NH4Cl +(NH4)2S a flesh-coloured precipitate was obtained.

(d) Carbon dioxide evolved on heating strongly. Substance insoluble in water, but on adding HCl a gas was evolved with effervescence, which rendered limewater turbid. No precipitate with the first three group reagents, but a white one with (NH) HO + NH, Cl + (NH4)2 C Og. Flame coloration dull red.

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