An unknown hydrate of cobalt(II)cyanide,Co(CN)2 • XH₂O,is heated to give 32.7% water.What is the water of crystallization (X)for the hydrate?

Question

Quizplus · Accepted Answer

The molar mass of Co(CN)2 is 118.94 g/mol (Co = 58.93, C = 12.01 x 2, N = 14.01 x 2). The mass of water (H2O) is 18.015 g/mol. If the hydrate gives off 32.7% water upon heating, we can set up the equation: (18.015X / [118.94 + 18.015X]) = 0.327, where X is the number of water molecules. Solving for X gives approximately 3, indicating the hydrate is Co(CN)2 • 3H2O.

An Unknown Hydrate of Cobalt(II)cyanide,Co(CN)2 • XH₂O,is Heated to Give