Question

Give reasons: 

(i) Use of a mild base like baking soda provides relief on the area stung by honeybee. 

(ii) Baking powder is added to make the cakes spongy and soft. 

(iii) The colour of blue copper sulphate crystals changes to white on heating.

Answer 1

(i) When a honeybee stings a person, this means it releases an acidic liquid (formic acid) into the body. This causes too much pain and irritation. As we know that baking soda (sodium hydrogen carbonate NaHCO₃) is a mild non-corrosive base. It can be used to neutralize an acid. 

Hence, when it is applied to the stung area, it reduces the effect of acid by neutralizing the excess acid. As a result, the pain and irritation is reduced. 

(ii) Baking powder, which is a mixture of baking soda and tartaric acid. When baking soda is heated or mixed in water, the reaction takes place is given as: 

Carbon dioxide released during the reaction causes the bread or cake dough to rise which makes them soft and spongy.

(iii) The colour of blue copper sulphate crystals changes to white on heating because: 

a. Blue copper sulphate crystals contain water of crystallization. 

b. When we heat the crystals, the water is removed. 

c. As a result, the salt turns white.