Blue and White Copper Sulfate

Problem Because the light blue color of the solid copper sulfate hydrate is identical to the aqueous solution, students should be convinced that the 

Material Test tubes, burner, copper sulfate hydrate (CuS04 5 H20). 

Procedure Fill a test tube with several spatula tips of copper sulfate hydrate and clamp the test tube slanted pointing downwards. Heat the salt intensely. Cool the white salt and then add several drops of water. 

Observation A white substance remains from the blue copper salt water forms during the heating process and drips out of the test tube. When water is added to the white substance, light blue copper salt returns, the contents of the glass become quite hot. 

Tip If portions of the substances are quantitatively weighed before and after the experiment, one achieves a good result, which shows the contents of 5 mol water molecules per mol copper sulfate hydrate, thereby establishing the existence of copper sulfate pentahydrate. 

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