Question

If percentage of water of crystallization in mgso4.X h2o is13

Answer 1

When the mass on subsequent weighings stays constant, you know all the water of crystallisation has driven off by the heat. This is the white anhydrous copper(II) sulphate. The formula mass Mr can then be calculated as follows: from the calculation a few lines above Mr CuSO4.5H2O = 160 + (5 x 18) = 250.