(e) White subliinate on heating. Substance dissolved in water and gave no precipitate with BaCl but a white one with AgNO„, insoluble in NHO, No precipitate with any of the group reagents, but gave a smell of ammonia on heating with NaHO. (f) Oxygen evolved on heating. Substance soluble in water, gave no precipitate with the first three group reagents, but a white one with (NH) HO + NH,CI+(NH),CO, Flame coloration green. 61. Six substances gave the following reaction when examined by means of Table B. Name each sub stance. (a) White and unfused on heating. Yields when heated on charcoal with sodium carbonate, a malleable bead which leaves a black mark on paper. (6) Infusible and disappears on heating. Deflagrates when heated with potassium nitrate. (c) Infusible when heated. Microcosmic salt bead colourless. Blue mass after heating on charcoal, moistening with CoCl, and heating again. (d) White and infusible. When heated with H, SO, evolves gas which etches glass. (e) Infusible, but darkens in colour on heating. Fused with NaHCO3, yields a brittle bead. (f) Fused but not volatilized on heating. Yields malleable metallic bead when heated on charcoal with NaHCO3. 62. (a) Give the four group reagents, and state the metals precipitated by each. (b) What are the metals of Group V.? 63. Write out the tests for silver. 64. Write out the tests for mercurous salts. 65. (a) Write out the tests for lead. (6) How is lead chloride distinguished from the chlorides of silver and mercury? (c) Give two methods for separating lead from silver and mercury. 66. How can you separate the metals in a solution containing silver, mercury, and lead? 67. (a) What happens when H2S is added to a solution of a mercuric salt? (b) What is "white precipitate"? 68. Why does lead occur both in the silver and copper groups? 69. (a) What is the action of water on salts of bismuth? (b) How is lead chromate distinguished from bismuth chromate ? 70. (a) What is the action of KCN and of H2SO upon copper sulphide? (6) What happens when (NH)HO is added to a solution of copper sulphate? 71. (a) What is the action of KCN and of H2SO upon cadmium sulphide? (6) Give two methods for the separation of copper from cadmium. 72. (a) Why is the filtrate from the silver group boiled down with hydrochloric acid before precipitating with H,S? (b) What is the action of (NH4)2S2 on the sul phides of the following metals — lead, antimony, copper, bismuth, tin, and cadmium ? (c) What is the action of nitric acid upon sulphides of copper, mercury, bismuth, and cadmium ? 73. (a) What reactions take place when mercuric chloride is added to stannic chloride and stannous chloride? (b) How is purple of Cassius obtained? 74. (a) What is the reaction of zinc upon an acid solution of antimony contained in a platinum vessel? (b) Describe Marsh's test for antimony. (c) What is the action of sulphuretted hydrogen upon an antimony mirror? 75. (a) What is the action of silver nitrate upon an acid, neutral, and alkaline solution of arsenious acid? (b) Give the formula of Scheele's green, and state how it may be obtained. (c) Describe Marsh's test for arsenic, and point out how it serves to distinguish that metal from antimony. (d) Describe Reinsch's test for arsenic. (e) Mention several ways of distinguishing an antimony from an arsenic mirror. (ƒ) State all the dry reactions for arsenic. 76. (a) What is the action of ammonium carbonate upon the sulphides of arsenic, antimony, and tin? (6) How is tin separated from antimony? 77. (a) How is Prussian blue obtained, and what is its formula? (b) How is Turnbull's blue obtained? (c) How are ferrous and ferric salts distinguished by the ferro- and ferri-cyanides of potassium? 78. (a) When a solution of the metals of the iron group is precipitated with ammonium sulphide, what causes the filtrate to have a brown colour? (b) What are the blow-pipe tests for nickel? 79. (a) What is the action of potassium cyanide upon solutions of nickel and cobalt? (6) How would you separate a solution of the chlorides of nickel and cobalt? (c) What is the action of potassium nitrite upon solutions of nickel and cobalt? 80. How can a solution of zinc hydrate in caustic potash be re-precipitated? 81. (a) How can a solution of aluminium hydrate in caustic potash be re-precipitated? (b) How can you distinguish between the hydrate and phosphate of aluminium? 82. (a) What happens when ammonia is added to a solution of manganese containing ammonium chloride? (6) What substance is formed when manganese compounds are fused with a mixture of potassium nitrate and carbonate? (c) How would you separate a solution containing the nitrates of iron, zinc, and manganese? 83. (a) How would you separate analytically a solution of nickel, cobalt, and chromium? (6) How would you separate analytically a solution containing iron, zinc, chromium, and manganese? 88. (a) What is the action of hydrochloric acid M upon the sulphides of iron, zinc, nickel, manganese, and cobalt? (b) What is the action of barium carbonate upon a cold solution of each of the following metals-iron, ▾ nickel, zinc, chromium, and manganese? (c) How is aluminium distinguished from zinc ? 85. Mention three characteristic tests for barium. 86. How is strontium distinguished from barium ? 87. How are strontium and calcium distinguished from each other? 88. (a) What is the action of strong alcohol upon the chlorides of barium and strontium, and upon the nitrates of strontium and calcium? (6) How are barium, strontium, and calcium separated from each other? (c) What is the action of acetic acid upon the chromates of barium and strontium? 89. What are the tests for magnesium ? 90. What is precipitated on adding platinum chloride to potassium chloride? Give its formula. 91. (a) What is the action of platinum chloride upon ammonium chloride? Give its formula. (b) How are ammonium salts distinguished from those of potassium ? 92. How are potassium salts distinguished from those of sodium? 93. Describe how magnesium, potassium, sodium, and ammonium are separated. 94. How are organic and inorganic acids distguished? |