Determine the mass fraction of water in copper sulfate (CuSO4 × 5H2O).

In order to find the mass fraction of water in CuSO4 * 5H2O in copper sulfate, we can act in at least two ways.

Let’s look at the first method.

Let’s calculate the molar mass of copper sulfate:

Mr (CuSO4 * 5H20) = Mr (Cu) + Mr (S) + 4Mr (0) + 5 * 2 * Mr (H) + 5 * Mr (0) = 64 + 32 + 64 + 10 + 80 = 250 grams / mol.

Let’s calculate the molar mass of water:

Mr (5H20) = 5 * 2 * Mr (H) + 5 * Mr (0) = 10 + 80 = 90 grams / mol.

To calculate the mass fraction of water:

w (H2O) = 90/250 * 100% = 36%.

Answer: 36% mass fraction of water.