Question

Give reasons for each of the following.
(i) On addition of water to quicklime, along with formation of Ca(OH)₂ , energy is produced.
(ii) Burns caused by steam are more severe than the burns by boiling water
(iii) Tap water cannot be used to prepare silver nitrate solution
(iv) Cl displaces bromine from KBr
(v) Mountaineers carry oxygen cylinders with them.

Answer 1

Reasons

Explanation:

(i) When quick lime is added to water filled in a bucket, it reacts vigorously with water to produce slaked lime releasing a large amount of heat. This is an exothermic reaction.

(ii) Steam has more heat energy than water due to its latent heat of vaporization, so it causes severe burns than boiling water.

(iii) Tap water contains chloride dissolved in water. These chloride ions will precipitate AgNO3 solution to form a precipitate of AgCl. Hence it is not used for preparation of silver nitrate.

(iv) Chlorine is more reactive than bromine, so it displaces bromine from sodium bromide.

(v) While climbing mountains, as the altitude rises, the amount of oxygen in the air decreases. So mountaineers carry oxygen cylinders.