CHAPTER XL.

PLATINUM. Pt=194.9.

1. FIND the percentage composition of (a) potassium K.PtCl, (B) ammonium (NH),PtCl chloroplatinate.

2. 112.3 grams of platinic chloride are heated, what volume of chlorine at 182o C. is given off?

3. Find the percentage composition of the green salt of Magnus (N,H.PtCl ̧).

4, 400 grams of ammonium chloroplatinate are heated, how much platinum sponge is left?

5.

(NH),PtCl = Pt + 2HCl + 2NH ̧ + 4C1.

6

Find the formula of a substance containing nitrogen 13.83 per cent., hydrogen 2.96 per cent., platinum 48.13 per cent., and chlorine 35.07 per cent.

6. 100 grams of platinum black unite directly with 73.5 grams of arsenic. Find a formula for the alloy, and calculate how much arsenic is required by the formula.

7. 6.981 grams of potassium chloroplatinate lose, according to Berzelius, 2·024 grams of chlorine when heated. Find the exact atomic weight of platinum.

K.PtCl = 2KCl+Pt+ 4Cl.

8. What volume of chlorine at 30° C. can be obtained from 100 grams of platinic chloride?

How much platinous chloride is required to give 10 litres of chlorine at 350° C. ?

PtCl2 = Pt+ 2C1.

10. 100 grams of platinum (sp. heat 0.03243) were heated in a furnace and plunged into a vessel of water, weighing when reduced to water 976 grams. The temperature of the water rose from 10° C. to 15o C., what was the temperature of the furnace ?

11. How much does a 100-gram weight of platinum (A 21-2) lose in air at 15o C. ?

12. How many grains of normal air are displaced by (a) the Imperial Standard Pound of Platinum (A 21.1572), and by (B) the Quartz Standard Pound (A 2-605) ?