49. If 3 grams of potassium permanganate are dissolved in a litre of water, to how much iron does 1 c.c. of the solution correspond? 50. A solution of 0.985 gram of black-band ironstone required 55.5 c.c. of a solution of potassium permanganate, What is the per containing 3 grams of the salt per litre. centage of iron in the ore? 10FeSO4 + KMn ̧ ̧ + 8H2SO 2 = 2 8 = 5Fe ̧3SO, + K2SO, + 2MnSO, + 8H ̧0. 4 51. How much potassium dichromate is required to convert one gram of iron from ferrous into ferric salt? 52. A balloon containing 1000 cub. metres is to be filled with hydrogen, when it has gone up to such a height that the pressure is 480 m.m. and the temperature – 30o C. How many kilograms of iron must be heated in steam? 3Fe + 4H,O= Fe ̧0, + 4H,. 3 4 53. How much potassium permanganate is required to convert one gram of iron from ferrous to ferric salt? = 4 = K ̧SO ̧ + 2MnSO ̧ + 5Fe̱ ̧3SO + 8H2O. 54. 0.2 gram of levigated iron when dissolved in acid required 30 c.c. of solution of potassium permanganate, containing 3 grams of the salt per litre. What is the percentage of iron? = K2SO, + 2MnSO ̧ + 5Fe̟.3SO, + 8H ̧0. 4 55. 3 c.c. of a solution of ferrous sulphate required 22.5 c.c. of a solution of potassium dichromate containing 4.9 grams of the salt per litre. How much iron is there in 1 c.c. of the solution? 56. How much potassium dichromate must be dissolved in a litre of water, that 1 c.c. of the solution may be equivalent to 0.0056 gram of iron? 57. From how many litres of air at 13° C. is the oxygen removed by a kilogram of iron in rusting? 2Fe +30= Fe2O ̧ 58. A balloon 100 feet in diameter is to be filled with hydrogen, how many tonnes of iron must be dissolved in acid ? Fe + 2HCl = FeCl ̧ + H ̧. 59. What volume of gaseous hydrogen chloride must be dissolved in water to act upon 89 grams of iron? And what volume of chlorine must be passed into the solution to convert the ferrous into ferric salt? 60. Calculate the percentage composition of a sample of Swedish steel which gave the following results, (a) 7·791 grams gave 0.208 gram of carbon dioxide, (B) 10.758 grams gave 0.004 gram of barium sulphate, (y) 10.758 grams gave 0.011 gram of graphite and 0·006 gram of silica, (8) 10-785 grams gave 0.018 gram of manganoso-manganic oxide. 61. 10 grams of ferrous oxalate when heated in hydrogen gave a mixture of iron and ferrous oxide. The product when dissolved in acid gave 300 c.c. of hydrogen measured over water at 10° C. Find the percentage of iron and of ferrous oxide in the residue. FeC20,2H,O= 2H2O + CO2+ CO + FeO. 2 FeC,O,2H,O=2H2O + 2CO2+ Fe. 62. Some steel-grey crystals in a Carinthian blast furnace were found to contain iron 76.23 per cent., and oxygen 23.76 per cent. Find the formula of the oxide. 63. Steam is passed over 9.7 grams of ferrous chloride heated in a tube. What does the resulting hydrogen measure over water at 20° C. and 700 m.m. ? 64. 1.25 gram of ferric oxide was reduced by hydrogen and the metal dissolved in dilute acid. The hydrogen evolved measured 382.6 c.c. over water at 17° C. and 750 m.m. Find the atomic weight of iron. 65. A salt of iron contains iron 43.75 per cent., sulphur 18.75 per cent., and oxygen 37.5 per cent. mula. Find its for 66. What volume of sulphur dioxide at 10° C. must be passed into a boiling solution of ferric chloride containing 437 grams of iron to reduce it to ferrous chloride? FeCl + 2H2O + SO2 = 2FeC1, + 2HCl + H2SO. 2 CHAPTER XXXII. COBALT. Co = 59. NICKEL. Ni = 58. 1. A SUBSTANCE contains cobalt 35.54 per cent., 45.18 per cent., and sulphur 19.28 per cent. formula. arsenic Find its 2. Find the percentage composition of nickelous oxide (NiO). 3. Find the percentage composition of cobaltous sulphate (COSO.7H ̧0). 4. What volume of hydrogen at 15° C. is required to reduce 100 grams of cobaltic oxide ? 5. How much nickelic oxide can be obtained by heating 100 grams of nickelous nitrate? 20 2Ni (NO),6H ̧0 = 12H ̧0+ N ̧0 ̧+ Ni̟ ̧ ̧. N2 3 2 6. How much mercuric oxide is required to precipitate grams of nickel as nickelous oxide ? NiCl + HgO= HgCl, + NiO. 7. What volume of hydrogen at 17° C. is required to reduce 10 grams of nickelous oxide? 8. Find the percentage composition of potassium and nickel nitrite NiK, (NO)。 9. What volume of chlorine at 14° C. must be passed into a solution of 1000 grams of cobalt in presence of barium carbonate to precipitate them as cobaltic oxide? 10. 2CoCl + 3BaCO2 ̧ + Cl2 = 3BaCl ̧ + 3CO ̧ + Co ̧ ̧. 2 2 2 What volume of carbon monoxide at 1200° C. is set free in reducing 764 grams of nickelous oxide? NiO+CCO + Ni. 11. Find the percentage composition of potassium cobalticyanide (K ̧Co ̧C12N12). 2 12 12. What volume of bromine (A 3) is required to precipitate 10 grams of cobalt in presence of barium carbonate as cobaltic oxide ? 2CoCl ̧ + 3BaCO ̧ + 2Br = 2BaCl ̧ + BaBr2 + 3CO + Co ̧ ̧. 13. What volume of carbon dioxide at 90° C. is given off on heating 170 grams of nickelous carbonate? 14. What volume of chlorine at 26° C. and 740 m. m. is evolved on boiling 10 grams of cobaltic oxide with hydrogen chloride? Co2O2+6HCl = 2CoCl ̧ + 3H ̧O + 2C1. 3 15. Find the formula of Schreibersite containing iron 57.11 per cent., nickel 28.35 per cent., and phosphorus 15.01 per cent. 16. Find the formula of a substance containing hydrogen 3.18 per cent., oxygen 33.88 per cent., nitrogen 14.84 per cent., sulphur 16.95 per cent., and nickel 31.15 per cent. |