8. 710 grams of chlorine are passed over a heated mixture of carbon and silicon dioxide. What volume of carbon monoxide and mass of silicon tetrachloride is formed?

9. 20 grams of silica are heated in the vapour of carbon disulphide, how much silicon sulphide and what volume of carbon dioxide at 13° C. is formed?

10. Find the mass of 1.5 litres of the vapour of silicon bromide (SiBr.) measured at 350° C. and 400 m.m.

11. What is the percentage composition of steatite MgSiO1. H2O?

4 11

12. Find the formula of a substance which contains silicon 26-27 per cent., calcium 18.43 per cent., magnesium 11.06 cent., oxygen per 44.24 cent. per

13. Find the mass in grams of a sphere of rock-crystal (A 2.65), 1 decimetre in diameter.

14. Wollastonite contains silica 51.31 per cent., alumina 1.37 per cent., lime 45.66 per cent., and magnesia 0.73 per cent. Find its formula.

15. Allophane contains silica 23-53 per cent., alumina 37.73 per cent., lime 1.92 per cent., and water 36.86 per Find its formula.

cent.

16. Find the volume of 208 grams of silicon fluoride (SiF) measured at 60° C.

17. How much silica is formed on burning 2 litres of hydrogen silicide measured at 30° C. ?

18. Find the formula of skolezite.which contains silica 46.2 per cent., alumina 26-28 per cent., lime 9.22 per cent., sodium oxide 5.16 per cent., and water (low) 13.25 per

cent.

19. Sahlite contains silica 54.02 per cent., lime 24.88 per cent., ferrous oxide 8.07 per cent., and magnesia 13.52 per cent. Find its formula.

20. What does one litre of silicon chloroform (SiHCl) at 180° C. weigh?

21. Silicon chloride vapour is 5.939 times as heavy as air, and silicon fluoride vapour is 3.6 times as heavy as air. Find in each case the double density referred to hydrogen.

22. What volume of chlorine at 10° C. must be used to make 100 grams of silicon tetrachloride?

SiO, +2C + 4C1 = 2CO + SiCl ̧.

23. How much does one litre of silicon tetrachloride (SiC) measured at 200° C. weigh?

24. Find the formula of a substance which contains magnesium 22.02 per cent., silicon 25.69 per cent., oxygen 44.04 per cent., and water 8.25 per cent. ?

25. Berzelius found topaz to contain alumina 58.38 per cent., silica 34-01 per cent., and fluorine 7.6 per cent. Find its formula.

26. Berzelius found Thomsonite to contain sodium oxide 4.53 per cent., lime 13.54 per cent., alumina 30.7 per cent., silica 38.3 per cent., and water 13 per cent. Find its for

mula.

27. Bonsdorff found Iolite to contain magnesia 10.45 per cent., ferrous oxide 5 per cent., alumina 32.88 per cent., silica 49.95 per cent., water and loss 1.75 per cent. Find its formula.

28. A specimen of orthoclase was found to contain silica 65.37 per cent., alumina 18.74 per cent., ferric oxide 0.13 per cent., lime 0.27 per cent., potassium oxide 12.98 per cent., and sodium oxide 2.48 per cent. Find the formula.

29. According to Schiel 0.6738 gram of silicon tetrachloride, when decomposed by ammonia, give 2-277 grams of silver chloride. Find the atomic weight of silicon.

SiCl + 2H2O + 4NH ̧ + 4AgNO ̧=4AgCl + SiO2+4NHNO。.

4

30. Find the percentage composition of triethyl silicoformate HSiO, (C2H2)з·

L. C. A.

11

CHAPTER XVIII.

PHOSPHORUS. P = 31.

1. How much phosphorus is there in 9.3 kilograms of calcium phosphate (Ca,2PO1)?

2. How much phosphorus is there in 700 grams of bone-ash (Ca 2PO)?

3. How much phosphorus is contained in 120 kilograms of bone-ash containing 85 per cent. of calcium phosphate (Ca,2PO1)?

4. The skeleton of a man weighs 24 lbs. and contains 58 per cent. of calcium phosphate (Ca,2PO,). Find the quantity of phosphorus present.

5. Find the mass of a round stick of phosphorus (▲ 1·83) 1 decimetre long and 2 centimetres across.

6. 100 litres of yellow (A 1-83) are converted into red (A 2.14) phosphorus, what is the volume of the latter variety?

7. One gram of phosphorus when burnt gives 2-29 grams of phosphorus pentoxide. Find the atomic weight of phosphorus.

8. Calculate the mass of 1.234 litres of phosphorus (P)

vapour.

9. How much phosphorus can be obtained from 169 tons of bones containing 53.7 per cent. of calcium phosphate (Ca22PO1)?

10. Phosphorus vapour is 4:42 times as heavy as air, find its molecular weight.

11. If one gram of phosphorus was found to form 2.903 grams of phosphorus pentoxide, what would the atomic weight of phosphorus be?

12.

How much phosphorus must be burnt to form 46 grams of phosphorus trioxide?

13. How much phosphorus must be burnt to form 46.86 grams of phosphorus pentoxide?

14.

What volume of air is required to burn 248 grams of phosphorus?

5

15. How much bone-ash containing 87 per cent. of calcium phosphate is required to make 200 kilograms of superphosphate of lime?

Ca ̧2PO1 + 2H2SO1 = 2CaSO ̧ + CaH2PO

16. How many kilograms of bone-ash containing 85 per cent. of calcium phosphate are required to make two tons of superphosphate of lime?

Ca 2PO4+2H,SO1 = 2CaSO4 + CaH2PO.

17. How much water must be added to 187 grams of phosphorus pentoxide to convert it into hydrogen (a) orthophosphate, (B) pyrophosphate, and (y) metaphosphate?