CHAPTER XIX.

ARSENIC. As = 75.

1. How many grams do two litres of arsenic (As) vapour at 327° C. weigh?

2. How much arsenic trioxide is formed by burning 3.567 grams of arsenic in oxygen?

3. Find the percentage composition of Proustite (Ag, ASS1).

4. 878 c.c. of air at 166° C. and 813 m.m. occupy what volume at -41° C. and 696 m.m.?

5. 100 grams of arsenic trioxide are heated with sulphur, what volume of sulphur dioxide and mass of orpiment are formed?

6. In a case of poisoning 11.73 grains of arsenic trisulphide were found, to how much arsenic trioxide does this correspond?

7. 50 grams of arsenic trioxide are heated with sulphur, what volume of sulphur dioxide at 39° C. is formed?

2As,O,+98=2As ̧S2+3SO,.

8. Find the mass of 56 c.c. of the vapour of arsenic trichloride (AsCl2) measured at 271-5° C.

9. A room 15 feet long and 10 feet wide and high is covered with a paper containing 0.78 grains of Scheele's green (CuHASO,) per square foot. How much arsenic is there in the room?

10. The vapour of arsenic trioxide is 13.85 times as heavy as air, find its double-density referred to hydrogen.

11. 4 litres of hydrogen sulphide at 13° C. are passed into a solution of arsenic trioxide, how much arsenic trisulphide precipitates?

12. How much zinc is required to make a litre of hydrogen arsenide?

6Zn + 6H2SO + As2O2 = 6ZnSO, +3H2O+2H2As.

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13. Find the percentage composition of Scheele's green (CUHASO2).

14. What does one litre of hydrogen arsenide (H ̧As) weigh?

15. What volume of hydrogen arsenide at 15o C. can be formed from one gram of arsenic trioxide ?

16. 4.95 grams of arsenic trioxide are heated with hydrogen nitrate, what volume of nitrogen trioxide at 50° C. and 800 m.m. is given off?

17.

What volume is occupied by 4 grams of cacodyl As, (CH), vapour at 210° C. and 780 m.m. ?

18. Find the percentage composition of Schweinfurt green (Cu2C,H,O̟ ̧. зCuAs ̧0).

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19. What volume of hydrogen sulphide at 20° C. is required to precipitate the arsenic from 100 grams of arsenic trioxide ?

20.

How much zinc is dissolved in forming 1.37 litres of hydrogen arsenide at 40° C. and 600 m.m.?

6Zn + As2O2+ 6H2SO1 = 6ZnSO ̧ + 3H ̧O + 2H ̧As.

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21. Find the percentage composition of (a) realgar As̟S,, (B) orpiment As,S,, (y) arsenic pentasulphide As ̧S.

22. The specific heat of arsenic is 0.0814, and 96.15 parts of arsenic combine with 3.85 parts of hydrogen. Find the atomic weight of the element.

CHAPTER XX.

ANTIMONY. Sb = 120.

BISMUTH. Bi = 208.

1. How much antimony is there in 1020 kilograms of the trisulphide (Sb,S,)?

2. A sheet of antimony (A 6.7) is 20 c.m. long, 10 c.m. wide, and 1 m.m. thick; find its mass.

3. What volume is occupied by 100 grams of (a) arsenic A 5.8, (6) antimony ▲ 6-8, and (y) bismuth ▲ 9.9?

4. Type metal is an alloy of 80 parts of lead (A 11.3) and 20 parts of antimony (A 6-7). Find the density of the alloy, supposing that no change of volume takes place after the fusion.

5. How much common salt is required to give chlorine enough to convert 100 grams of antimony into the trichloride?

6NaCl + 3MnO2+ 6H2SO ̧

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3MnSO, + 3Na2SO̟ ̧ + 6H ̧O + 6C1, 28b+6C12SbCl..

6. 33.6 grams of antimony trisulphide are dissolved in hydrogen chloride. What volume of hydrogen sulphide under a pressure of 567 m.m. is evolved?

Sb2S2+6HCl = 2SbCl ̧ + 3H ̧S.

7. A piece of antimony was converted into the tribromide by absorbing 187 c.c. of bromine vapour. What was the mass of the antimony?

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8. According to Cooke 100 grams of antimony tribromide (SbBr) contain antimony 33-3335 per cent. and bromine 66.6665 per cent. If Br 80, find the atomic weight of antimony.

9. What volume of hydrogen sulphide is evolved on dissolving 10 grams of antimony sulphide in hydrogen chloride?

Sb2S2+6HCl = 2SbCl ̧ + 3H ̧S.

10. How many grams do 20 litres of hydrogen antimonide (H,Sb) measured at 15° C. weigh?

11. Bismuth melts at 264° C., what temperature is this on the Fahrenheit and on the Réaumur scale ?

12. Find the percentage composition of the four oxides of bismuth, (a) Bi̟ O̟,, (ß) Bi̟,O,, (y)Bi̟ ̧O̟, (8) Bi̟O̟.

13. What volume of oxygen at 30° C. is given off on heating 100 grams of bismuth pentoxide ?

14. Arcet's alloy consists of 5 parts of lead (A 11.45), 3 parts of tin (A 7.3) and 8 parts of bismuth (A 9-9). Find the density of the alloy supposing that its volume is equal to the sum of the volumes of its constituents.

15. Wood's alloy consists of 2 parts of lead (▲ 11·45), 4 parts of tin (A 7-3), 2 parts of cadmium (A 8.7), and 8 parts of bismuth (A 9.9). Find the density of the alloy supposing that the fusion produces no permanent change of volume.