Determine the formula of a hydrate

You have 1.023g of CoSO4 hydrate. After heating and driving off all the water, the mass of the anhydride is 0.603 g. Determine the hydrate's chemical formula (number of waters attached).
The answer is CoSO4 • 6H2O -- Please explain how you get this, step by step

mass of CoSO4.xH2O (hydrate)= 1.023 g
mass of CoSO4 (anhydrate) = 0.603 g

mass of H2O removed after heating = mass of hydrate - mass of anhydrate
mass of H2O removed after heating = 1.023 g - 0.603 g = 0.42 g


Find the moles of CoSO4 and H2O from the given masses:
moles of CoSO4 = mass CoSO4 / molar mass = 0.603 g / 154.9958 g/mol
moles of CoSO4 = 0.00389 mol

moles of H2O in hydrate = moles of H2O removed = mass H2O / molar mass
moles of H2O = 0.42 g / 18 g/mol = 0.02333 mol


Divide moles of CoSO4 & H2O with the lowest number of moles among the two which is 0.00389 mol.

CoSO4 = 0.00389 mol / 0.00389 mol = 1
H2O = 0.02333 mol / 0.00389 mol = 6


Empirical Formula: CoSO4.6H2O