Science Lab Experiment: Properties of Hydrates
Object: To determine the special characteristics of hydrates.
Materials: test tube, stand and clamp, alcohol lamp, cobalt chloride, water
Method: A few grains of pink cobalt chloride were added to the test tube and heated
as shown in the diagram.
Observations: As the pink cobalt chloride was heated, a fine mist was noticed on the
inside of the test tube. The cobalt chloride turned blue. When a few
drops of water were added to the blue cobalt chloride, it turned back
to a pink colour.
Conclusions: It was concluded that cobalt chloride contained water which was driven
off by heating. This vapour condensed on the cool inside glass of the test
tube. When a few drops of water were added to the cobalt chloride, it turned
back to the pink colour, indicating that the water had been replaced. Blue
cobalt chloride can be used as an indicator of humidity.