Question

How would you prepare :

Copper sulphate crystals from a mixture of charcoal and black copper oxide.

Answer 1

Add 50 cm³ of diluted sulphuric acid in a beaker and warm it using a wire gauge. Small amounts of black cupric oxide should be added at a time, stirring the mixture until all of the oxide has dissolved and settled to the bottom. Pour it through a hot filter, collecting the filtrate in a china dish. After heating it to the point of crystallisation and letting it cool, it evaporates. Collect the copper (II) sulphate pentahydrate (CuSO₄.5H₂O), often known as blue vitriol, with bright blue (rhombic) crystals.

\[\ce{CuO + H2SO4 -> CuSO4 + H2O}\]

\[\ce{CuSO4 + 5H2O -> \underset{Blue vitroil}{CuSO4.5H2O}}\]