35. 2 grams of potassium are heated in ammonia, how much potassamide and what volume of hydrogen at 15° C. is formed?

36.

K+NH ̧ = KH ̧N + H.

10 grams of solution of ammonia when mixed with sodium hypobromite gave 1 litre of nitrogen at 7o C. Find the percentage of ammonia in the solution.

37.

3NaBrO + 2NH2 = 3NaBr + 3H2O + N ̧.

2

What is the volume of 20 grams of ammonia (NH)

at 12o C. and 730 m.m.?

38. 25.82 litres of nitric oxide diffuse through a certain apparatus in 50 minutes, what volume of hydrogen will diffuse under the same conditions?

39. A litre of hydrogen nitrate (A 1-4 containing 70 per cent. of real acid) is mixed with water and caused to act upon excess of copper. What volume of nitric oxide is given off?

40.

3Cu+8HNO, 3Cu2NO, + 4H,0 + 2NO.

=

2

Excess of phosphorus is burnt in 10 litres of nitrous oxide, how much phosphorus pentoxide is formed, and what volume of nitrogen at 15° C. is left?

41. 2 litres of nitryl chloride at 15° C. are passed over warm silver nitrate, how much nitrogen pentoxide is formed? NO,CI+ AgNO1 = AgCl + N ̧ ̧.

42. Find the percentage composition of dimercurammonium iodide NHg I.

2

CHAPTER IX.

THE ATMOSPHERE.

A LITRE of normal air weighs 1.293 grams.

Air contains 23.8 per cent. of oxygen by mass, and 20.9 per cent. of oxygen by volume.

1. The pressure on 134 c.c. of air is increased from 480 m.m. to 1200 m.m. Find the new volume.

2. 476 c.c. of air are heated to 637° C. Find the new volume.

3. What is the mass of 500 cubic metres of air at 21° C. ?

4. Find the mass of 640 c. c. of air measured at 546° C. and 712 m.m.

5. Westminster Hall is 290 feet long, 68 feet wide, and 110 feet high, how many tons of air does it contain?

6. The area of the basin of the Thames is 6000 square miles. A rainfall of 3·937 inches upon it is how many cubic metres of water?

7. 200 c.c. of air are measured at 20° C. and 740 m.m. What is the normal volume?

8. Find the normal volume of 250 litres of air measured at 30° C. and 740 m.m.

9. 20 c.c. of air are mixed with 30 c.c. of hydrogen and exploded, what volumes of what gases are left?

10. On Oct. 14th, 1881, the pressure of the wind at Greenwich was 53 lbs. per square foot, how many grams per square centimetre is the pressure equivalent to? The pressure on the same day at Birkenhead was 77 lbs. per square foot, how many tons pressure was there on a wall 50 feet high and 60 feet long? If the rate of the wind was 65 miles per hour, how many feet per second was it?

11. How many pounds of air at 15° C. are there in a room 30 feet long, 22 feet wide, and 15 feet high? And what mass of oxygen is there in the air?

12. How many kilograms of air are there in a room 17 feet 6 inches long, 14 feet wide and 10 feet high?

13. It is calculated that the mass of the atmosphere is equal to that of 581 000 cubic kilometres of copper (▲ 8-9). Find the radius of an iron (A 7·8) sphere equal in mass to the atmosphere.

14. How much phosphorus must be burnt in what volume of air at 0° C. to make 15.8 litres of nitrogen at 13o C.?

15. What volume of air containing 21 per cent. of oxygen by volume is required to burn 248 grams of phosphorus?

16. How much phosphorus is required to remove the oxygen from a litre of air?

17.

at 26° C.?

100

How much sulphur can be burnt in 20 litres of air

18. What volume of air at 21° C. must be passed over grams of copper to convert them into cupric oxide?

19. How much magnesium can be burnt in a globe containing 5 litres of air at 21° C. and 740 m.m.? Mg + 0 = MgO.

20. How much moist iron can be oxidized by a cubic metre of air at 13° C.?

2Fe +30= Fe2O..

21. In one of Dumas' experiments to determine the composition of air by passing it over heated copper:

Mass of tube and copper before the experiment 120

grams.

Calculate the percentage composition of air by mass and by volume.

the

22. How much phosphorus is required to remove all oxygen from 100 litres of air at 15° C. and 740 m.m.?

23. An inch of rain is how many tons of water on an acre?

24. 100 litres of air are passed over red-hot copper, how much does the copper increase in mass?

25. A magnesium (▲ 1·74) wire is burnt in a cylinder of oxygen at 0° C. When the temperature has again fallen to 0o C., the length of wire burnt is found to be equal to the distance through which the water has risen in the cylinder. If the wire be 1 m.m. in diameter, find the radius of the cylinder.

Mg + 0 = MgO.

26. A mass of air a mile square and 100 feet thick is saturated with aqueous vapour at 50° F. (the tension is 9.165 m.m.). If the temperature fall to 41° F. (the tension is 6.534 m.m.), how many tons of water precipitate?

27. 1000 cubic metres of gas at 18° C. and 765 m.m. are put into a balloon of 1250 cubic metres capacity. After ascending to a certain height the temperature is found to be 8° C. and the balloon is fully distended. Find the height of the barometer in the balloon and its distance from the earth. 500 grams of carbon are burnt in 60 cubic metres of air free from carbon dioxide at 14° C. Find the percentage of nitrogen, oxygen, and carbon dioxide in the air after the experiment.

28.

29. 146 c.c. of air at 10° C. and 730 m.m. are measured over water, what would the dry normal air measure?

30. A vessel of water at 99o C., weighing when reduced to water 50 kilos., was placed in a room 10 m. each way containing air at 0° C. and 760 m.m., the walls of which were impervious to heat. Find the temperature of the air and the increase in pressure on each sq. c.m. of the surface of the

room.