Question

What do you observe when:

(a) Blue vitriol is heated ?

(b) Washing soda is exposed to air ?

(c) Blue litmus solution is added to water ?

Answer 1

(a) Blue vitriol is blue in color as it contains 5 molecules of water of crystallization (CuSO₄H₂O). When it is heated, it loses water of crystallization and becomes anhydrous CuSO₄ which is grey-white in color.

(b) Washing soda (Na ₂CO₃.10H₂O) is a white crystalline substance and on exposure to air it gets changed the o white powder.

(c) Pure water is neutral to litmus which means that no change in the colour of blue or red litmus solution is observed when 1 treated with water.