Question

What happens when copper sulphate crystals are heated strongly? Explain with the help of an equation. What happens when a few drops of water are added to anhydrous copper sulphate? Explain with the help of an equation.

Answer 1

Hint :We know that the chemical formula of hydrated copper sulphate is $CuS{O}_4.5H_{2}O$ . It contains five molecules of water of crystallization. It appears as blue coloured crystals. On heating, blue coloured copper sulphate crystals become white.

Complete Step By Step Answer:
Hydrated copper sulphate i.e. is copper sulphate pentahydrate. It has five e water molecules of crystallization (or water of hydration) which means that five water molecules are present in crystals of copper sulphate. When copper sulphate pentahydrate is heated, it loses water of crystallization as a result of evaporation. Losing water of crystallization turns hydrated copper sulphate into anhydrous copper sulphate salt. Hydrated copper sulphate is blue coloured crystals.. Heating turns crystals into anhydrous crystals which are colourless. If heating continues, anhydrous copper sulphate undergoes decomposition to form copper $\left(II\right)$ oxide (cupric oxide) which is black in colour. Oxygen and sulphur dioxide are also released. The chemical reaction for the decomposition of copper sulphate on heating. On strong heating, blue copper sulphate crystals turn white due to formation of anhydrous copper sulphate.
 $CuS{O}_4.5H_{2}O\to CuS{O}_4+5H_{2}O$
Also, when water is added to anhydrous copper sulphate, it gets hydrated and turns blue.
 $CuS{O}_4+5H_{2}O\to CuS{O}_4.5H_{2}O$

Note :
Remember that Salts containing no water or crystallization are called anhydrous salts. Copper sulphate pentahydrate is a hydrated salt which on heating loses its five salts containing no water or crystallization are called anhydrous salts. Copper sulphate pentahydrate is a hydrated salt which on heating loses its.