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966. Name some of the most abundant minerals containing aluminium, and give the composition of cryolite, orthoclase, and wavellite.
967. By whom and when was the metal aluminium first prepared ? What are its properties ?
968. How is aluminium prepared on the large scale, and what is it chiefly used for ?
969. Find the quantity of sodium which is theoretically required to decompose 197 pounds of the double chloride of aluminium and sodium. How much potassium would be required for the same purpose ?
970. What is the composition of the ruby, and how may it be prepared artificially?
971. What is the action of the common acids and alkalies on aluminium ? Starting with metallic aluminium, how would you prepare
ash alum? 972. How are aluminium chloride and the double chloride of aluminium and sodium prepared ?
973. How are aluminium sulphate, aluin cake, and common alum respectively obtained ?
974. What is the constitution of the alums? Give the formulæ for each of the following-ammonia alum, chrome alum, and silver alum.
975. How much ammonia alum contains 156 grammes of aluminium ? How much aluminium sulphate and ammonium sulphate must be used to obtain 1,897 grammes of the alum?
976. What is a “mordant”? Explain how alum is used as a mordant.
977. What occurs when aluminium acetate solution is boiled ? How is the substavce used in calicoprinting ?
978. Give a short description of the manufacture of glass and of pottery.
979. What is pyrolusite, and how may manganese be prepared from it? What is the action of manganese on water?
980. Give a short account of each of the oxides of manganese, and state how they may be obtained from the dioxide.
981. Which oxide of manganese loses, when heated till constant, 3.37 per cent. of oxygen ?
982. How much pure manganese dioxide is required when heated in a current of hydrogen to yield 798 grammes of water ?
983. Express by equations the action of hydrochloric and sulphuric acids on each of the oxides of manganese.
984. What evidence is there for supposing the existence of a tetrachloride of manganese ?
985. How are manganate and permanganate of potassium prepared, and what are their properties ?
986. What is the action of each of the following bodies on solution of potassium permanganate? (a) hydrogen, (b) ammonia, (c) stibine, (d) ferrous sulphate, (e) oxalic acid, (f) sulphuretted hydrogen, (g) manganese chloride.
987. How is manganese dioxide recovered, by Weldon's process,
chloride ? 988. When the higher oxides of manganese are heated in a current of hydrogen, what body remains, and what are its properties?
989 2:6789 grammes of an oxide of manganese when heated till constant in hydrogen left a residue which weighed 2'4907 grammes. Find the composition of the oxide.
990. Give three distinct methods for ascertaining the quantity of Mno, in a sample of commercial manganese dioxide. Describe the advantages of each method.
991. Oʻ139 gramme of pyrolusite when treated with hydrochloric acid yielded enough chlorine to liberate 0°336 gramme iodine from potassium iodide. Find the percentage of MnO, in the pyrolusite.
992. Represent by equations the action of sulphuric acid, and of sulphuric acid in presence of potassium oxalate on manganese dioxide.
993. What happens when (a) manganese chloride and (6) manganese dioxide are strongly heated in air ?
994. How is potassium manganese alum prepared ? Give the proportions of each constituent required.
995. In an analysis of pyrolusite by Fresenius' method, the following results were obtained
2'2711 grammes of the oxide yielded 17091 gramme carbon dioxide. Find the percentage of Mno, in the oxide.
996. 0°7804 gramme of a hydrated oxide of manganese left, when heated in hydrogen, 0-5674 gramme residue. Find the percentage of manganese and the formula of the hydrate.
997. What weight of manganese dioxide when heated should yield 2.76 litres of oxygen at 14° C., and 754 m.m. pressure ?