Question

Hydrochloric acid reacts with a metal ‘A’ to form a gas ‘B’ which burns with a ‘pop’ sound. Sodium hydroxide solution also reacts with the same metal A on heating to form the same gas B.
Name A and B.
Write the chemical reaction of metal A with-
(a) Hydrochloric acid
(b) Sodium hydroxide solution

Answer 1

Hint: Generally metals react with hydrochloric acid and sodium hydroxide (base) and release a gas after their reaction. The gas comes out with a sound ‘pop’ during the reaction and releases some amount of energy (exothermic reaction).
Complete step by step answer:
- In the question it is given that a metal ‘A’ reacts with acid and with a base and forms a gas ‘B’.
- We have to find the metal ‘A’ and gas ‘B’ and have to write their chemical reactions.
- Generally zinc reacts with both acid and base and releases a gas of hydrogen.
 - The chemical reaction of Zinc with acid and base are as follows.
\[Zn+2HCl\to ZnC{{l}_{2}}+{{H}_{2}}(g)\]
- Zinc reacts with 2 moles of hydrochloric acid and forms one mole of zinc chloride and one mole of hydrogen gas as the products.
\[Zn+2NaOH\to N{{a}_{2}}Zn{{O}_{2}}+{{H}_{2}}(g)\]
- Zinc reacts with 2 moles of sodium hydroxide and forms one mole of sodium zincate and one mole of hydrogen gas as the products.
- So, in the above two reactions the gas which is released commonly is hydrogen gas.
- Therefore A = zinc and B = Hydrogen gas.
- The chemical reaction of metal A (zinc) with
(a) Hydrochloric acid
\[Zn+2HCl\to ZnC{{l}_{2}}+{{H}_{2}}(g)\]
(b) Sodium hydroxide solution
\[Zn+2NaOH\to N{{a}_{2}}Zn{{O}_{2}}+{{H}_{2}}(g)\]

Note:
Reaction of zinc metal with acid and a base are best examples of exothermic reaction. Because there is a liberation of hydrogen gas and some amount of energy during the reaction. If energy is absorbed during the reaction then the reaction is called endothermic reaction.