Question

During the reaction of some metals with dilute hydrochloric acid, following observations were made.
(i) The temperature of the reaction mixture rises when aluminium (Al) is added.
(ii) The reaction of sodium metal is found to be highly explosive.
(iii) Some bubbles of a gas are seen when lead (Pb) is reacted with the acid.
 

Answer 1

(i) The temperature of the reaction mixture rises when aluminium is added because it is an exothernic reaction.
(ii) Reaction of sodium metal is found to be highly explosive because it is an exothermic reaction.
(iii) When lead is treated with hydrochloric acid, bubbles of hydrogen gas are evolved.
Pb(s) + 2HCl(aq) ------> PbCl₂(aq) + H₂(g)