CHAPTER XIII. IODINE. I = 127. 1. How much ferric chloride is required to obtain the iodine from 100 tonnes of kelp, each tonne of which contains 4.07 kilograms of iodine? 2NaI + FeCl = 2NaCl + 2FeCl ̧ + I ̧. 2. How many times is solid iodine (A 4-94) heavier than an equal volume of its vapour measured at 350° C.? 3. Iodine vapour is 8.716 times as heavy as air, find its molecular weight. 4. 3.81 grams of iodine vapour mixed with hydrogen are passed through a red-hot tube, what volume of hydrogen iodide is formed? H+ I = HI. 5. What mass of hydrogen is there in 1 litre of hydrogen (a) bromide (HBr) and (B) iodide (HI)? 6. 20 grams of iodine are suspended in water, what volume of hydrogen sulphide at 15° C. is required to convert them into hydrogen iodide? 7. I2+H,S=S+2HI. How much iodine is there in a litre of a solution (A 1.7) containing 52 per cent. of hydrogen iodide (HI)? 8. How much iodine, phosphorus, and potassium iodide must be used to make 10 litres of gaseous hydrogen iodide at 15° C.? 101, +4P + 8KI + 16H,0 = 4K,HPO, + 28HI. 9. Find the percentage of iodine and of oxygen in iodine (a) pentoxide (1,0,) and (B) septoxide (1,0,). 10. Find the percentage composition of hydrogen (a) iodate (HIO) and (B) periodate (HIO). 11. 119 grams of iodine are suspended in water, what volume of chlorine is required to convert them into hydrogen iodate? I + 5C1 + 3H20 = 5HCl + HIO ̧. 12. 14 grams of potassium iodate are heated, what volume of oxygen at 13° C. is evolved? KIO2 = KI + 30. 13. How much phosphorus and iodine must be used to make 100 litres of hydrogen iodide at 30° C. and 740 m.m.? P+31 + 3H20 = H2PO2+3HI. 14. A balloon contains 5 litres of chlorine at 20° C. and 780 m.m., how much iodine must be thrown into it to obtain the monochloride? I + CI = ICI. 15. 0.1 gram of potassium dichromate is distilled with hydrogen chloride, how much iodine will the resulting chlorine set free from potassium iodide? K ̧Cr2O, + 14HCl = 7H ̧O + 2KCl + Cr ̧Cl ̧ + 6Cl. 7 2 KI+ Cl = KCl + I. L. C. A. 10 16. A mixture of potassium chloride, bromide, and iodide was precipitated by silver nitrate and the silver chloride bromide and iodide was found to weigh 15.57 grams; after heating with bromine water, the silver chloride and bromide weighed 14.69 grams; lastly after heating with chlorine water the precipitate weighed 12.2 grams. Find how much chlorine, bromine, and iodine was present in the mixture. 17. Find the percentage composition of iodoform (CHI2). CHAPTER XIV. FLUORINE. F=19. 1. WHAT mass of hydrogen fluoride can be obtained from 100 grams of fluor-spar? CaF2+ H2SO1 = CaSO1 + 2HF. 2 2. 100 grams of fluor-spar are heated with hydrogen sulphate, how much calcium sulphate is formed? CaF2+ H2SO1 = CaSO2+ 2HF. 2 4 3. What volume of hydrogen fluoride at 15° C. can be obtained from 7-8 grams of fluor-spar? 4. 468 grams of fluor-spar are heated with silicon dioxide and hydrogen sulphate. If the gas produced be passed into water, how much silicon dioxide and hydrogen fluosilicate is formed? 2CaF ̧ + SiO, + 2H2SO1 = 2CaSO, + 2H2O + SiF ̧. 2 4 5. 100 grams of fluor-spar gave, when heated with hydrogen sulphate, 174.5 grams of calcium sulphate. What is the atomic weight of fluorine? CaF2+ H2SO1 = CaSO ̧ + 2HF. 6. Find the percentage composition of (a) fluor-spar (CaF), (B) cryolite (NaAlF12). 2 7. 3.2617 grams of calcium fluoride gave 5.6867 grams of calcium sulphate. Find the atomic weight of fluorine. CaF ̧ + H2SO1 = CaSO1 + 2HF. 2 8. What volume of hydrogen fluoride at 20° C. can be obtained from 20 grams of cryolite? 9. Nå ̧AIF12+ 6H2SO1 = 3Na ̧SO, + A13SO̟ + 12HF. 12 4 4 What volume of hydrogen fluoride can be obtained from 50 grams of fluor-spar? 10. 150 c.c. of hydrogen fluoride are passed over heated sodium, how much sodium fluoride is formed? HF+Na = H+NaF. 11. Find the mass of 10 litres of hydrogen fluoride (HF) at 30° C. and 740 m.m. 12. Commercial hydrogen fluoride contains 35 per cent. of real acid, if 100 grams of it be heated with excess of hydrogen sulphate, what volume of gas (HF) at 20° C. and 750 m.m. is evolved? 13. To determine the density of hydrogen fluoride, a balloon holding 4394-7 c.c. was filled with the vapour at 30° C. and 745 m.m. The following results were obtained: Mass of the balloon and vapour 428.255 grams. Find the density of hydrogen fluoride. 14. What difference does the result obtained in 13 make in the answers of 11 and 12? |