Question

Hydrochloric acid reacts with a metal X to form a gas Y which burns with a 'pop' sound. Sodium hydroxide solution also reacts with the same metal X (on heating) to form the same gas Y.
(a) Name X and Y
(b) Write the chemical equation of the reaction of metal X with (i) hydrochloric acid, and (ii) sodium hydroxide solution.

Answer 1

(a) X is the metal zinc (Zn) and Y is hydrogen gas.
Zinc reacts with hydrochloric acid and forms zinc chloride salt with the liberation of hydrogen gas (Y), which burns with a 'pop' sound. Zinc displaces hydrogen from hydrochloric acid.
Hence, X is zinc and Y is hydrogen.

(b) The chemical equation is as follows.

(i) Zn + 2HCl $\to$ZnCl₂ + H₂ ↑

(ii) 2NaOH + Zn $\to$Na₂ZnO₂ + H₂