This Chemistry Equation Is Confusing, Can Someone Help Me?

Cof2 is a unique salt in that it forms a hydrate with water.If 10.055g of hydrated salt is heated for several minutes the resulting mass of the salt is 7.65g. After heating a second time vigorously for several minutes we find a mass of 5.85g.Why was additional mass lost after the second heating? Assuming that 5.85g is the mass of the anhydrous salt what is the ratio of water molecules to the salt?

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Summerrae

asked 1 year ago

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1. Mass was lost during the second heating because additional water was being driven from the compound.

2. 5.85 g of cobalt fluoride is about .0604 moles. Cobalt fluoride has a molar mass of about 96.93 g/mol; water has a molar mass of about 18.015 g/mol. We can find the number of water molecules tied up in cobalt fluoride n-hydrate by solving the equation
(.0604 mol)(96.93 g/mol + n (18.015 g/mol)) = 10.055 g
n(18.015 g) = (10.055 g)/(.0604 mol) - 96.93 g/mol = 69.544 g/mol
n = (69.544 g/mol)/(18.015 g) = 3.86/mol (3.86 water molecules per 1 salt molecule)

The ratio of water molecules to the salt is about 3.86 for the given assumptions.