25 g of copper sulfate was dissolved in 200 ml of water. What is the mass fraction of copper sulfate in the resulting solution?

Copper sulfate has the formula CuSO4 5H2O, is a blue crystal.

1) M (CuSO4 5H2O) = M (CuSO4) + 5 * M (H2O) = 159.6 + 5 * 18 = 249.6 g / mol.

2) Mass fraction of copper sulfate in copper sulfate is the ratio of the molar mass of CuSO4 to the molar mass of the entire compound:

ω (CuSO4) = M (CuSO4) / M (CuSO4 5H2O) = 100% * 159.6 / 249.6 = 63.9422%.

Then its mass will be 63.9422% of the total mass of the compound:

m (CuSO4) = 63.9422% * 25/100% = 15.9855 g.

Let’s find the mass of the new solution:

we have given the volume of water, it must be converted into mass. Density (p) of water ≈ 1 g / ml.

p = m / V,

m = p * V = 200 * 1 = 200 g.

m (CuSO4 5H2O) + m (H2O) = 25 + 200 = 225 g.

Since we know the mass of copper sulfate, we can find the percentage in this solution:

ω (CuSO4) = m (CuSO4) / m (solution) = 100% * 15.9855 / 225 = 7.1046%.