hydrogen oxalate and sulphate. What volume of carbon dioxide at 30° C. is given off? K ̧Cr2O,+5H2SO, +3CH ̧0 = 2HKSO2+ Cr23SO, 2 7 31. 4 4 + 7H2O + 6CO,. 21 litres of chlorine at 10° C. are passed over a heated mixture of chromic oxide and charcoal. How much chromic chloride is formed? 32. 10 grams of lead chromate are heated with fluorspar and hydrogen sulphate, what volume of chromium hexafluoride at 20° C. is obtained? PbCrO+3CaF+4H SO=4H,O+3CaSO + PbSO+ CrF. 2 What 33. 100 grams of potassium dichromate are boiled with equal quantities of ammonium and sodium nitrates. volume of nitrogen at 13° C. and 740 m.m. is evolved? K ̧Cr2O,+4NH.NO, + 4NaNO ̧ = 5H ̧0+2KNO ̧ 2 7 3 34. What volume of nitrogen measured over water at 30° C. and 740 m.m. is evolved on heating 70 grams of ammonium dichromate ? (NH),Cr2O, = Cr ̧0 ̧ + 4H ̧0 + N ̧. 2 2 3 2 CHAPTER XXXIV. TIN. Sn = 118. 1. FIND the percentage composition of tinstone (SnO,). 2. Find the formula of tin-pyrites which contains copper 29.53 per cent., iron 13.07 per cent., tin 27.53 per cent., and sulphur 29.86 per cent. 3. A sheet of tin-foil (A7-3) is a yard long, a foot wide, and '01 of an inch thick, find its mass in grams. 4. 100 grams of tin (A 7.3) are melted with 100 grams of lead (A 11-45). Find the density of the alloy supposing that no change of volume takes place. 5. 10 grams of tin were boiled with hydrogen chloride, when 1.12 litres of hydrogen had been given off the tin was found to weigh 4·1 grams. Find the atomic weight of tin. Sn+ 2HCl=SnCl, + H2. 6. 100 grams of tin were heated with hydrogen nitrate, after ignition the stannic oxide weighed 127·1 grams. What is the atomic weight of tin? 7. What volume of air at 13o C. is required to convert 590 grams of tin into the dioxide ? L. C. A. Sn + O1 = SnO,. 15 8. 17 grams of tin were dissolved in sodium hydrate, what volume of hydrogen at 15° C. was evolved? Sn+2HNaO+H2O= Na SnO, +4H. 9. The vapour of stannic chloride is 9.199 times heavier than air, and that of stannous chloride 13.08 times heavier. Find the double densities of these vapours referred to hydrogen. 10. What volume of gaseous hydrogen chloride at 60° C. is required to convert 50 grams of tin into stannous chloride? Sn + 2HCl = SnCl ̧ + H ̧. 11. What volume of chlorine at 26° C. is absorbed in converting 1000 grams of tin into the tetrachloride? Sn+4Cl = SnCl ̧. 12. 40 grams of bromine are converted into hydrogen bromide which is passed over heated tin; what volume of hydrogen at 15o C. is set free? 2HBr + Sn = SnBr2 + 2H. 13. How much "tin-salts" can be made from 488 grams of tin? Sn + 2HCl + 2H,O= H2+ SnCl,2H,O. 14. Find the percentage composition of stannous metastannate (SnH,Sn,O,,). 15. What volume of hydrogen sulphide at 26° C. is required to precipitate the tin from a solution of 110 grams of "tin-salts"? SnCl22H2O + H2S = 2HCl + 2H2O + SnS. 16. A substance contains tin 64.84 per cent., and sulphur 35.16 per cent. Find its formula. 17. What volume of hydrogen at 15o C. is evolved on dissolving 10 grams of tin in hydrogen chloride? Sn + 2HCl = SnCl ̧ + H ̧. 18. What volume of chlorine at 10° C. must be passed over 80 grams of tin to convert them into stannic chloride. Sn + 4Cl = SnCl. 4° 19. 40 grams of tin were dissolved in hydrogen chloride, what volume of hydrogen at 39° C. was given off? 20. Find the formula of a substance containing sodium 16.2 per cent., tin 41.56 per cent., oxygen 16.9 per cent., and water 25.34 per cent. 21. A sheet of iron (▲ 7·8) 1 m. square and 1 m.m. thick is dipped into melted tin. If its original mass be increased by, what is the thickness of the layer of tin (▲ 7·3) ? 22. How many grams does a spherical globule of tin (A 7.3) 2 m.m. in diameter weigh? 23. 9 grams of tin are dissolved in aqua regia, what volume of hydrogen sulphide at 15° C. and 770 m.m. is required to precipitate them? SnCl + 2H,S= 4HCl + SnS ̧. 24. 10 c.c. of a solution of stannous chloride, when mixed with excess of ferric chloride, required 47 c.c. of a solution of potassium permanganate containing 3 grams of the salt per litre. How much tin was there in 1 c.c. of the original solution? SnCl2+ + FeCl = 2FeCl + SnCl. KMn ̧ ̧ + 10FeCl2 + 16HCl 2 2 gen cent. 25. Find the formula of a substance containing hydro0.84 per cent., tin 74.06 per cent., and oxygen 25.1 per 26. 4 grams of tin are heated with 200 c.c. of hydrogen sulphide at 10° C. and 740 m.m. How much does the tin increase in mass? Sn + H2S = SnS + H ̧. 27. Find the formula of a substance containing nitrogen 7.63 per cent., hydrogen 2.17 per cent., chlorine 58.03 per cent., and tin 32.16 per cent. 28. A circular sheet of card-board 1 m. across is covered on one side with a sheet of tin-foil (▲ 7·3) 0·02 m.m. thick. By how many grams does the cardboard increase in mass? |