Sidebilder
PDF
ePub

17. 20 grams of witherite are dissolved in hydrogen chloride, how much crystallized barium chloride and what volume of carbon dioxide is formed?

BaCO3 + 2HCl + H2O = CO ̧ + BaCl ̧ . 2H ̧O,

2

18. Crystallized strontium hydrate is soluble in 50 times its mass of water, how much hydrogen sulphate will 100 grams of such a solution precipitate?

H ̧SÃO ̧ . 8H2O+ H2SO1 = 10H ̧0+ SrSO.

2

19. If air contains 0.037 per cent. by volume of carbon dioxide, find the mass of the precipitate produced on drawing 1000 litres of air through baryta water,

CO,+ HạBaO, = H,O + BaCO..

2

sus

20. 100 grams of hydrated barium dioxide are pended in water, what volume of carbon dioxide at 13° C. is required to precipitate the barium?

21.

BaOg. 6H,O + CO,= BaCO,+H,O,+5H,O.

2

What volume of carbon dioxide at 10° C. is required to precipitate the barium from a solution of 100 grams of crystallized barium chloride in presence of ammonia ?

2NH, + BaCl,2H2O + CO2 = BaCO2 + H ̧O + 2NHCl.

2

22. If 14 grams of barium dioxide are heated, what volume of oxygen at 15° C. and 700 m.m. is given off? BaO = BaO + O,

2

23. On the addition of ammonium carbonate to a mixture of calcium and barium chlorides, the precipitate weighed 10 grams. On redissolving the precipitate and adding ammonium sulphate, the precipitate weighed 12

STRONTIUM. BARIUM.

195

grams. How much barium and how much calcium was present?

4NH ̧ + [BaCa] Cl ̧ + 2H2O+2CO2 = 4NH C1 + [BaCa] CO2

2

4

[BaCa] C1, + 2H2SO1 = 4HCl + [BaCa] SO.

24. According to Marignac, 10 grams of crystallized strontium chloride give 6.8855 grams of strontium sulphate. Find the atomic weight of strontium.

SrCl ̧ . 6H ̧O + H2SO1 = 6H ̧O + 2HCl + SrSO.

CHAPTER XXVII.

ALUMINIUM. Al = 27.

1. How much aluminium is there in 100 grams of (a) cryolite Al,Na F12, (B) common alum K,A1,4SO. 24H ̧O?

6 12'

2. A sheet of aluminium (A 2.67) is 1 m.m. thick, 1 d.m. across, and 1 m. long. Find its mass.

3. 54 grams of aluminium are dissolved in potassium hydrate, what volume of hydrogen is given off?

Al ̧ + 2HKO + 2H2O = 2KA10, + 6H.

4. What volume of oxygen is required to burn 10 grams of aluminium ?

[ocr errors]

5. How much aluminium is there in 100 grams of turquois (AlРO̟ ̧. HА10.2H ̧0) ?

2 8

6. What volume of oxygen at 15° C. is required to burn 50 grams of aluminium?

Al, +30= Al ̧ ̧.

7. 50 grams of oxygen are heated with 54 grams of aluminium, what volume of oxygen is left uncombined? Al, +30= Al ̧ ̧•

8. 100 grams of ammonia-alum are heated, how much alumina is left?

(NH,),A14SO,.24H,O = (NH,),SO,+Al,O,

[blocks in formation]

9. How much alumina and how much silica is there in 100 grams of clay (Al,O,. 2SiO)?

10. How much potassium-alum (K,A1,4SO. 24H,O) can be made from 1000 000 grams of clay (Al,O,. 2SiO2)? What volume of ammonia can be obtained from 100 grams of ammonia-alum?

11.

(NH),A14SO. 24H ̧O + 2HKO = KA14SO ̧ . 24H2O

12.

2

+ 2H2O + 2NH ̧.

7.339 litres of the vapour of aluminium chloride at 546o C. are passed over heated sodium, how much aluminium is set free?

[blocks in formation]

13. A mineral was found to contain alumina 68.31 per cent., ferric oxide 337 per cent., ferrous oxide 2.06 per cent., and magnesia 26-26 per cent. Find its formula.

14. Find the percentage composition of aluminium and sodium chloride. (Al,NaCl.)

15. Find the percentage composition of diaspore. (AI,O,. H2O.)

16. 5 grams of aluminium are heated in sulphur vapour. How much aluminium sulphide is formed?

[ocr errors][subsumed]

17. 10 kilograms of alumina will form how much potash-alum?

Al ̧0 + 3H2SO + K2SO, +21H2O = K ̧AI,4SO ̧ . 24H,O.

18. The vapour of aluminium chloride is 9.34 times as heavy as air, find its molecular weight.

19. 20 grams of cryolite are heated with hydrogen sulphate, what volume of hydrogen fluoride at 20° C. is given off?

No¿Al ̧F ̧ + 6H ̧SO1 = 3Na ̧SO + A13SO̟ + 12HF.

2 12

4

20. Find the mass of 10 litres of the vapour of aluminium chloride (Al,Cl) measured at 300° C.

21. Aluminium bronze contains 10 per cent. of aluminium (A 2-6) and 90 per cent. of copper (A 8.9). Find the density of the alloy supposing that no change of volume has taken place.

22. What volume of chlorine at 15° C. and 750 m.m. is required to convert 10 grams of alumina into aluminium chloride?

A1,0 ̧ + 3C + 6C1 = 3CO + A1C ̧.

23. Find a formula for ultramarine which contains aluminium 14.5 per cent., silicon 17.5 per cent., sodium 16 per cent., sulphur 14.2 per cent., and oxygen 37.8 per cent.

24. 1 gram of aluminium when dissolved in hydrogen chloride gave 1.271 lit. of hydrogen at 10° C. Find the atomic weight of aluminium.

[blocks in formation]

25. Steam is passed over 20 grams of gently heated aluminium chloride, what volume of hydrogen chloride at 150° C. is formed?

Al ̧Cl ̧ + 3H ̧0 = Al ̧02+ 6HCl.

6

3

« ForrigeFortsett »