When copper sulfate (CuSO4) reacts with water (H2O), the product is still copper sulfate. However, it is the hydrated form of the salt and has 5 water molecules. Thus, the product is called copper sulfate pentahydrate. The relevant chemical reaction is:
`CuSO_4 + 5H_2O -> CuSO_4 .5H_2O`
Thus, copper sulfate reacts with water in a 1:5 ratio and the product is copper sulfate pentahydrate.
The anhydrous Copper sulfate salt is pale green in color, whereas the hydrated salt, copper sulfate pentahydrate is blue in color. Copper sulfate has several applications in industry and research. It is toxic to microorganisms and is commonly used to kill them. For example, rain water harvesting systems are cleaned with a solution of copper sulfate before the first rain, to ensure no biological contamination of water supplies.
Hope this helps.