2. Two methods to test the presence of water will be introduced.
1) Using dry cobalt chloride paper
2) Anhydrous copper (II) sulphate.
What is water?
Water is a compound which contains
2 Hydrogen molecules, and 1 Oxygen
molecule to form H2O. Water exists in three states – solid, liquid and gas.

3. Dry cobalt chloride paper 2 pieces Unknown substance several
Materials and Apparatus:
Dry cobalt chloride paper pieces
Unknown substance several
Dropper dropper
Forceps forceps
Cobalt Chloride Paper:
stored in a desiccator
should be blue in colour
Procedure:
Add a drop of unknown
substance to a piece of dry
cobalt chloride paper.

4. Possible Results
1) The dry cobalt chloride paper turns from blue to pink, it proves that there is water in the unknown liquid.
2) The color of the dry blue cobalt chloride
paper remains unchanged, it shows that water is absent in the liquid.

5. Chemical Symbol: Anhydrous CuSO4
Anhydrous means ‘without water’.
Anhydrous Copper (II) Sulphate is white in color.
Reaction between water and Anhydrous Copper (II) Sulphate is reversible.
Results:
Anhydrous CuSO4 is dry, when water is added, it turns from white to the familiar hydrated blue crystals. This proves that water is present.

6. There are two ways to test for the presence of water
There are two ways to test for the presence of water. The use of dry cobalt chloride paper is relatively an easier process than using Anhydrous Copper (II) Sulphate.
Therefore, dry cobalt chloride paper is more commonly use than Anhydrous Copper (II) Sulphate.