Ammonium Chlor-platinate, (NH₄)₂PtCl₆

Ammonium Chlor-platinate, (NH₄)₂PtCl₆, is closely similar in appearance to the potassium salt, with which it is isomorphous. It crystallises in regular octahedra.

The solubility of ammonium chlor-platinate in water at various temperatures is as follows:

Temperature ° C.	15.5	100
Grams (NH4)2PtCl6 per 100 grams H2O	0.666	1.25

When heated, ammonium chlor-platinate decomposes in accordance with the equation:

3(NH₄)₂PtCl₆ = 3Pt + 16HCl + 2NH₄Cl + 2N₂,

the metal being left behind as a dull grey, soft and porous mass known as spongy platinum or platinum sponge. The density of the salt is 3.034.