Question #eb1dc

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SCooke
Mar 19, 2016

Divide the mass of hydrated water (moles or mass, depending on the intent) by the mass of the entire compound.

Explanation:

A hydrated compound is usually indicated by a numerical prefix (Greek) in the name, or the written number in the formula. Hydrates are complete water molecules associated with a salt, so they are always indicated as a unit in the formula.

For example, copper (II) sulfate pentahydrate is the copper sulfate molecule with five (penta) water molecules. The formula is

CuSO4o5(H2O). The mole ratio of water to the entire molecule is 5 moles H2O/1 mole CuSO4. The mass ratio is 90g/159.5g or 0.564 (56.4%). The amount of water in the entire molecule is 90/249.5 = 0.36 or 36%.

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