(a) While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid ?
(b) Dry hydrogen chloride gas does not change the colour of dry litmus paper. Why ?
(a) The process of diluting an acid is highly exothermic, and on the addition of acid to the water the excess heat is absorbed by water.
(b) Because HCl does not form H+/H3O+ ions in dry condition.