Growing Crystals of Copper Sulphate

It may be necessary to wear disposable gloves while doing this. Do not eat the crystals because copper sulphate is harmful. Clean any spillages straight away. Keep this away from small children and pets. Beside the test apparatus, place a label saying: Harmful – Do not touch; or something to that effect. Wash your hands after touching the test equipment.

Dissolve some copper sulphate in some warm distilled water in a flask until it’s saturated – you’ll know when to stop because when no more dissolves, it starts to deposit on the bottom of the flask. Decant this solution into a new flask trying to leave behind the undissolved copper sulphate. Place a pencil diametrically across the top of the second flask, which has a thin piece of string tied to its middle and a small piece of copper sulphate crystal tied to the other end, completely immersed in the solution.

It may be necessary to add some more distilled water as the days go by to counter evaporation and to make sure that there’s enough solution to completely cover the crystal. The cooler the temperature of the solution, the larger the crystal ultimately grows to. You may like to test this if you’re performing this as an experiment rather than a curiosity – leave one flask in direct sunlight and another in the shade as a control. Measure the temperature every six hours until they both stop growing and compare temperature variance to crystal size.