Crystallization of Copper sulphate | Chemistry | purification of Copper The process that separates pure substances from their solutions in the form of Crystals is known as crystallization. It is a physical change. Crystals of salt are obtained by the evaporation of seawater. Similarly, crystals of copper sulphate can be obtained by adding copper sulphate powder to the boiling solution of water and dilute sulphuric acid. This mixture when filtered and allowed to cool produces crystals of copper s