CHAPTER XXXV.

LEAD. Pb = 207.

1. FIND the number of pounds of sheet lead, one square foot of which weighs 5 lbs., on a roof which is 36 feet 9 inches long and 16 feet 8 inches wide.

2. How much litharge can be obtained from 40.5 kilos. of lead, and what volume of oxygen is absorbed in the process? Pb+0=PbO.

3. Find the percentage of lead in (a) Anglesite PbSO, and (B) Cerussite PbCO,.

4. What volume of oxygen is absorbed in converting 37.1 kilos. of lead into litharge?

Pb+OPbO.

5. 21.94 grams of litharge gave 20.37 grams of lead, what is the atomic weight of the metal?

6. How many shot 1 m.m. in diameter can be made from 1 000 000 grams of lead (▲ 11·46)?

7. 100 grams of lead (A 11.45) are melted with 300 grams of tin (47.3). If the volume remains unchanged, what is the density of the alloy ?

8. How much lead dioxide can be obtained from 20 grams of lead nitrate?

Pb2NO, + CaOCI, + H ̧O = 2HCl + Ca2NO ̧ + PbO ̧.

2

9. Find the percentage composition of lead chromate (PbCrO1).

10. 5 grams of lead chloride gave 5.16 grams of silver chloride, find the atomic weight of lead..

PbCl + 2AgNO2 = Pb2NO, + 2AgCl.

2

11. How much lead acetate can be made from 6.69 kilos. of litharge?

PbO + 2HC2H2O, + 2H,O= Pb (C,H ̧0 ̧),зH ̧0.

3

2

12. Find the percentage of lead in crystallized lead acetate (Pb (CH ̧0 ̧),зH ̧0).

2

13. How much pyroligneous acid containing 40 per cent. of hydrogen acetate is required to form a kilogram of lead acetate ?

PbO + 2HCH ̧O̟ ̧ + 2H ̧O = Pb (C ̧¤ ̧ ̧), 3H ̧0.

3

14. Berzelius found that 100 grams of litharge contain 7.1724 grams of oxygen. Find the atomic weight of lead. PbO Pb+ 0.

15. If a lead wire 1 inch in diameter will just carry 20 lbs., how many kilos. will a wire 1 m.m. in radius carry?

16. 100 grams of lead nitrate are heated, what volume of nitrogen tetroxide at 150° C. and 730 m.m. is evolved? Pb2NO1 = PbO + 0 + 2NO,.

17. Water from a leaden cistern 3 by 2 by 1 metre gave on evaporation with hydrogen sulphate 113 grams of lead sulphate (PbSO). Find the percentage of lead in the

water.

18. 100 grams of white lead boiled with dilute hydrogen nitrate gave 6 litres of carbon dioxide at 15° C. Find the percentage of lead carbonate, lead hydrate and impurities in the white lead.

Pьн ̧0,2PьCO2+6HNO ̧=3Pb2NO ̧ + 4H ̧O + 2CO,.

19.

2

Find the formula of a substance containing carbon 7.96 per cent., hydrogen 0.99 per cent., oxygen 10.61 per cent., lead 68.66 per cent., and chlorine 11.79 per cent.

20. 100 grams of lead fluoride are heated with hydrogen sulphate, what volume of hydrogen fluoride at 70° C. and 700 m.m. is given off?

PbF2+H2SO1 = PbSO+ 2HF.

2

4

21. 1000 grams of lead nitrate are heated, how much litharge is left, and what volume of nitrogen tetroxide at 90° C. is given off?

Pb2NO1 = PbO+0+2NO,.

22. According to Dumas 100 grams of red-lead when heated give 2·4 grams of oxygen. Find the formula of redlead.

(PbO), (PbO)=(PbO)m+n+Om

23. Find the formula of Cassel yellow which contains lead 90.05 per cent., chlorine 3.86 per cent., and oxygen 6.09 per cent.

24. According to Stas 100 parts of lead form 159.9703 parts of lead nitrate; what is the atomic weight of the metal?

CHAPTER XXXVI.

COPPER. Cu = 63.3.

1. 1.3305 grams of copper when heated in oxygen gave 1.6675 grams of cupric oxide, find the atomic weight of copper.

Cu + O CuO.

=

2. What volume of hydrogen sulphate (▲ 1·84) and mass of copper are required to yield 30 litres of sulphur dioxide? Cu + 2H,SO = CuSO ̧ + 2H ̧O + SO。.

3. Chlorine is passed over 100 grams of copper, how much cupric chloride is formed?

4. How much blue vitriol can be obtained from 1000 kilograms of cupric oxide?

CuO+ H2SO2+ 4H2O = CuSO,5H2O.

5. How many grams of cupric oxide are formed on heating 10 lbs. of copper in air?

6. The vapour of cuprous chloride is 6.93 times as heavy as air, find its double-density referred to hydrogen.

7. 10 litres of air are passed over heated copper, how much cupric oxide is formed?

Cu + O CuO.

8. Find the percentage composition of crystallized cupric sulphate (CuSO ̧ . 5H ̧0).

9. 10 litres of hydrogen at 30° C. are passed over hot cupric oxide, how much copper is set free and what volume of steam at 300° C. is formed?

10.

A substance contains copper 57.5 per cent., carbon 5.4 per cent., hydrogen 0.9 per cent., and oxygen 36.2 per cent.; find its formula.

11. How many kilograms of hydrogen sulphate must be heated with copper to give 300 kilograms of sulphur dioxide, and how much crystallized copper sulphate can be obtained from the solution?

Cu + 2H SO, +3H2O = CuSO,5H2O+SO,.

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12. 99 grams of copper are dissolved in hydrogen nitrate, what volume of nitric oxide at 39° C. is formed?

3Cu + 8HNO2 = 3Cu2NO ̧ + 4H ̧0 + 2NO.

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13. A spiral of copper wire is heated by electricity in a litre of air at 15o C., how much cupric oxide is formed? Cu + 0 = CuO.

14. A current of electricity is passed through acidulated water and through an acidulated solution of cupric sulphate. While 246 c.c. of hydrogen measured over water at 15° C. and 750 m.m. are evolved, how much copper precipitates? H2O = H2+ 0.

2

=

2

CuSO4 + H2O Cu + H2SO, + O.

2

2

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15. 3 grams of cuprous hydride are dissolved in hydrogen chloride, what volume of hydrogen at 100° C. and 746 m.m. is evolved?