8. Find the mass of a stick of potassium hydrate (▲ 2·2) 1 c.m. across and 10 c.m. long.

9. How much potassium nitrate can be obtained from 1000 kilograms of potassium carbonate?

K ̧CO2+2HNO2 = 2KNO ̧ + H ̧0+ CO2.

3

3

2

10. 10 grams of potassium bicarbonate are heated, what volume of carbon dioxide at 30° C. is given off?

2HKCO,K,CO2+ H2O+CO,.

=

3

2

11. If 260 grams of potassium chlorate are heated, what volume of oxygen at 94.8° C. and 960 m.m. is evolved? KC102 = KCl + 30.

12. 4 grams of potassium and hydrogen carbonate are dissolved in hydrogen chloride, what volume of carbon dioxide at 52° C. is given off?

KHCO3 + HCl = KCl + H2O + CO2.

13. A substance contains potassium 28.25 per cent., chlorine 25.64 per cent., and oxygen 46.11

its formula.

per cent. Find

14. 100 grams of nitre are heated, what volume of oxygen at 39° C. is evolved?

15. Find the mass of a potassium (▲ 0·86) wire 2 m.m. in diameter and 1 decim. long.

16. Potassium (▲ 0·86) absorbs 126 times its volume of hydrogen, find a formula for the body formed.

17. 20 grams

of potassium nitrate are heated with potassium dichromate; what mass of gas is evolved, and what is the volume of each gas at 20° C. ?

18.

2KNO ̧ + K ̧CÃ ̧0,= 2K ̧CrO + 2NO, +0.

2 2 7

4

Find the percentage composition of potassium silicofluoride K,SiF

6'

19. A gasogen holding 4 litres is charged by decomposing 4 ounces of hydrogen and potassium carbonate with tartaric acid, but the water is forgotten. If the temperature of the room be 10° C. what is the pressure of the gas in atmospheres ?

2HKCO ̧+ H ̧T = 2H ̧0 + K ̧T + 2CO,.

20. Supposing that the decomposition of powder is expressed by the equation

S2+6C + 2KNO, = 6CO, +2N, +2K ̧S,

(a) What volume of gas at 0° C. is formed by 100 grams of powder, and (B) what volume would the gas occupy at 1000° C. ?

21. 10 grams of potassium fluoride are heated with hydrogen sulphate, what volume of hydrogen fluoride at 90° C. is given off?

2KF + H2SO1 = K2SO̟ ̧ + 2HF.

4

22. What volume of oxygen at 15° C. is required to convert 10 grams of potassium into the tetroxide ?

23. 5 grams of potassium tetroxide are thrown into water and the solution is boiled, what volume of oxygen at 100° C. is given off?

K ̧0,+H,O=2HKO + 30.

24. What volume of hydrogen sulphide at 15° C. and 730 m.m. must be passed into a solution of 100 grams of potassium bronate to reduce it to bromide?

2KBrO,+6H,S= 2KBr+ 6H2O + 68.

3

25. Find the percentage composition of feldspar KAI Si 016

CHAPTER XXIII.

SODIUM. Na = 23.

1. FIND the percentage composition of (a) dry (Na,CO2) and (B) crystallized (Na,CO,10H,O) sodium carbonate.

2. A stick of sodium (A 0.97) is 1 c.m. square and 1 decim. long. Find its mass.

3. What volume of oxygen at 200° C. is required to convert 100 grams of sodium into the dioxide?

4. How much sodium can be obtained from 20 kilograms of sodium carbonate, and what volume of carbon monoxide is formed in the process?

5. How much sodium can be obtained from one kilogram of sodium carbonate?

Na,CO2+2C = 3CO + 2Na.

6. Find the percentage composition of common salt (NaCl).

7. The specific heat of sodium is 0.2934, and 39.32 grams of sodium unite with 136-765 grams of bromine.

atomic weight of sodium.

Find the

8. How much slaked lime and sodium carbonate must be used to make a kilogram of sodium hydrate?

Na,CO2+H,CaO, = CaCO̟ ̧ + 2HNaO.

3

2

2

3

9. How many pounds of common salt are required to yield 500 lbs. of salt-cake?

2NaCl + H2SO1 = 2HCl + Na2SO

4

10. How much dry sodium carbonate can be made from 500 kilograms of common salt?

2NaCl + H2SO1 = 2HCl + Na2SO

4

Na2SO + CaCO2+ 4C = 4CO + CaS + Na ̧CO2.

4

11. If 100 grams of common salt are decomposed by hydrogen sulphate, how much sodium sulphate, and what volume of hydrogen chloride is formed?

2NaCl + H2SO1 = Na2SO + 2HC].

4

12. A sample of soda-ash is found to contain 56 per cent. of sodium oxide, how much sodium carbonate per cent. is there in the ash?

13. Find the percentage of sodium sulphate and of water in Glauber's salts (Na,SO,. 10H2O).

14. If 10 grams of sodium sulphite are dissolved in acid, what volume of sulphur dioxide at 12° C. is given off? Na2SO2+ 2HCl = 2NaCl + H2O + SO2·

3

2

15. If 100 grams of sodium sulphate are heated with charcoal, how much sodium sulphide and what volume of carbon monoxide at 15° C. is formed?

Na,SO + 4C = Na2S + 4CO.

4

16. 1000 kilograms of common salt are converted into

salt cake, how much sodium sulphate and what volume of hydrogen chloride gas is formed?

2NaCl + H2SO1 = Na2SO + 2HCl.

4

17. How many kilos. of soda crystals containing 3 per cent. of impurity, and how many kilos. of hydrochloric acid (A 1-21) containing 480 times its volume of the gas can be formed from the materials in the last question?

Na2SO1 + 4C + CaCO2 = CaS + 4CO + Na ̧CO2

4

18. 10 grams of sodium and hydrogen sulphite are heated; what volume of sulphur dioxide is given off?

2NaHSO ̧ = Na2SO ̧+ H ̧O + SO̟ ̧.

2

19. A cubical crystal of rock-salt (▲ 2·16) weighs 43.2 grams; find the length of its edge.

20. Sodium hydride (40.959) contains 46 parts of sodium (497) and 1 part of hydrogen, find the apparent density of the solid hydrogen.

21. In trade analyses the atomic weight of sodium is often taken as 24 instead of 23; find the error per cent. thus introduced if the result be calculated (a) as sodium, (B) as sodium carbonate.

22. 1.221 grams of a mixture of potassium and sodium carbonates gave 1.231 grams of the mixed chlorides, from which 2.87 grams of silver chloride were formed. Find the percentage composition of the mixture.

[Na,K2]CO2+ 2HCl = 2[NaK]Cl + H2O + CO2,

[NaK]Cl + AgNO, = AgCl + [NaK]NO,.