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8. How many pounds of zinc can be dissolved by 600 pounds of hydrogen sulphate diluted with water?

Zn + H2SO = ZnSO4 + H ̧.

9. How much zinc can be dissolved by 450 pounds of solution of hydrogen chloride containing 30 per cent. of real acid?

Zn + 2HCl = ZnCl ̧ + H ̧.

10. What volume of air is required to oxidize 1000 kilograms of zinc blende?

2ZnS+30,= 2ZnO +2SO,.

11. Cadmium becomes brittle at 180° F., melts at 242° F., and boils at 1580° F. What are these temperatures on the Centigrade scale?

12. How much crystallized cadmium bromide can be made from 100 grams of cadmium, and what volume of hydrogen is given off?

Cd + 2HBr + 4H,O= CdBr ̧4H2O ÷ H2.

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13. A metallic chloride is found to contain 38.66 per cent. of chlorine, and its vapour is 8 times as heavy as air. Find the atomic weight of the metal and the formula of the chloride.

14. How much zinc must be dissolved in dilute hydrogen sulphate to fill a wedge-shaped india-rubber bag 1 m. long, 60 c.m. broad, and 340 m.m. deep at the thickest end, with hydrogen at 15o C., and 780 m.m. ?

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15. What volume of hydrogen measured over water at 15° C. and 760 m.m. is set free on dissolving 0.5 grams of zinc in acid?

Zn + 2HCl = ZnCl ̧ + H ̧.

16. Find the formula of a substance containing zinc 58.56 per cent., carbon 4.05 per cent., oxygen 25.23 per cent., and water 12.16 per cent.

17. 4 litres of chlorine at 30° C. and 770 m.m. are passed over heated zinc, how much zinc chloride is formed? Zn + Cl2 = ZnCl ̧.

18. Brass consists of two parts of copper alloyed with one part of zinc. Find an approximate formula for it.

19. 0.5 grams of zinc when dissolved in acid gave 183 c.c. of hydrogen measured over water at 9o C., the barometer standing at 748 m.m. Find the equivalent of

the metal.

zn + h cl = zn cl + h.

20. What volume of hydrogen can be obtained by dissolving 471 grams of zinc in acid, and how long will the gas take to diffuse through an apparatus which allows 16 litres of nitric oxide (NO) to pass in 100 seconds?

Zn + 2HCl = ZnCl, + H2.

21. A quantity of potassium nitrate is boiled with zinc, iron, and potassium hydrate, how much zinc is dissolved during the evolution of one litre of ammonia at 10o C. and 730 m.m.?

14HKO + 8Zn + 2KNO2 = 8K ̧ZnO, + 4H ̧O + 2NH ̧.

22. A substance contains zinc 52.84 per cent., carbon 39.03 per cent., and hydrogen 8.13 per cent. Find its formula.

CHAPTER XXX.

MANGANESE. Mn = 55.

1. FIND the percentage of manganese in (a) pyrolusite MnO,, (B) Braunite MnO

2. Manganese has the specific heat 0.114, and 69.92 grams of it combine with 30.38 grams of oxygen; find the atomic weight of the metal.

3. A pellet of manganese weighed in ether (▲ 7024) 14-6212 grams, and in chloroform (A 1·5252) 12.9756 grams, find the density of the metal.

4. According to v. Hauer, manganous sulphate (MnSO,) contains 42.39 per cent. of oxygen. Find the atomic weight of the metal.

5. What is the mass of a manganese wire (▲ 8) 1 m. long and 1 m.m. in radius?

6. 100 grams of manganous oxide are heated to whiteness with charcoal, how much manganese and what volume of carbon monoxide are formed?

MnO+CMn+ CO.

7. What volume of oxygen at 12° C. can be made by heating 500 grams of manganese dioxide ?

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8. What volume of oxygen at 750 m.m. can be made by heating 500 grams of manganese dioxide with hydrogen sulphate ?

MnO2+ H2SO1 = MnSO4 + H2O + 0.

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9. How many grams of oxygen are there in 100 grams of potassium permanganate (K,Mn2O ̧)?

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10. How much manganese ore containing 85 per cent. of the dioxide is required to give 300 lbs. of chlorine? MnO2+ 4HCl = MnCl ̧ + 2H ̧O + Cl ̧.

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11. Find the percentage composition of manganesealum (K ̧Mn4SO. 24H ̧O).

12. How much manganese dioxide can be made from a cubic metre of "red liquor" containing 0.3 gram of manganous chloride in 1 c.c.?

MnCl, + H ̧CaO, + 0 = CaCl ̧ + H2O + MnO̟ ̧.

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13. Find the percentage composition of manganese blende (MnS).

14. How much manganous sulphate can be obtained from a kilogram of manganese dioxide?

MnO2+ H2SO1 = H2O+O+ MnSO.

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15. 487 grams of manganese dioxide are heated, what volume of oxygen at 15° C. is given off?

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16. 10 grams of manganese ore mixed with hydrogen sulphate oxidized 10-953 grams of hydrogen oxalate. Find the percentage of manganese dioxide in the ore.

MnO2+ C2H2O̟. 2H2O + H2SO ̧ = MnSO ̧ + 2CO, + 4H ̧O.

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17. A sample of pyrolusite is found to contain 34 per cent. of oxygen as the dioxide. What volume of chlorine can be obtained by heating 20 grams of the mineral with hydrogen chloride?

MnO, +4HCl = 2H ̧O + MnCl ̧ + Cl ̧.

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18. 4.9435 grams of commercial manganese dioxide, when warmed with hydrogen sulphate and oxalate, caused the evolution of 2·18 grams of carbon dioxide. Find the percentage of real dioxide in the sample.

MnO2+ C2H2O1. 2H2O + H2SO1 = MnSO1 + 4H2O + 2CO ̧

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19. 0.4 gram of "manganese" containing 90 per cent. of real dioxide is distilled with hydrogen chloride. How much iodine is set free on leading the evolved chlorine into solution of potassium iodide ?

MnO, + 4HCl = 2H2O + MnCl, + Cl ̧.

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20. 2 grams of dry manganous sulphate are dissolved and precipitated by barium chloride. What will the mass of the precipitate be if (i) Mn = 55, and (ii) Mn = 54 ?

21.

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How much manganese dioxide must be heated to

form 1000 litres of oxygen at 20° C. ?

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What volume of air is required to oxidize the manganese in 1000 litres of 'red liquor' containing 100 grams of manganous chloride per litre ?

MnCl, + H ̧CaO, + 0 = H2O + CaCl ̧ + MnO ̧.

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23. How much manganese dioxide is required to give 2.7 litres of oxygen at 14° C. and 754 m.m.?

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24. A gram of partially dried hydrogen oxalate when warmed with hydrogen sulphate and manganese dioxide gave 492 c.c. of carbon dioxide measured over water at 20° C. and 757.4 m.m. Find the percentage of water still left in

the oxalate.

CH2O+H2SO, + MnO, MnSO, + 2H2O+ 2CO,.

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