1. TESTING FOR WATER Lesson Outcome
Through experimentation understand the properties of water (ie. Water of crystallization & freezing point).

2. WATER OF CRYSTALLISATION
Sometimes ionic substances crystallise from aqueous solutions with the molecules of water still attached.
This is called water of crystallisation.
It is written in the form CaSO4.2H2O (calcium sulphate dihydrate)
Heating the solid can drive off the water, leaving the anhydrous (without water) ionic substance.

3. Heating Hydrated Cobalt Chloride
Turned to a blue powder called anhydrous cobalt chloride and gave off water vapour. The blue powder gradually turned pink again when it was left standing in the room.

4. HEATING COPPER SULPHATE
WHY DOES WHITE COPPER SULPHATE TURN BLUE WHEN WATER IS ADDED?

5. When heated, hydrous crystals lose their water of crystallisation and turn into a powder. They may also lose their colour. They are then said to be anhydrous.