Why a reaction of a metal with acid liberates gases. And how do we detect them?

Why a reaction of a metal with acid liberates gases. And how do we detect them?

Page 22 Question 2

Acids in a solution form H⁺ ion. Metals are electron donor; they donate electrons to H+.  Addition of electron to  H⁺ forms a hydrogen molecule. The hydrogen molecule is a gas and does not dissolve in water. This gas escapes out.

HA(Acid) (in aqueous medium)—-> H⁺ + A^–

M —-> M⁺ + e^–

2H⁺ + 2e^– —> H₂(gas)

Hydrogen gas (H₂) is an inflammable gas, when we bring this gas to a burner it burns spontaneously.

Next: A metal compound which reacts with acid and extinguishes the fire.

See also: Why we do not keep curd and sour substances in Brass container.

Related posts:

A metal compound forms effervescence dil. HCl. This gas extinguishes fire While diluting an acid, why is it recommended that the acid should Give an example of a double displacement reaction other than the one given in Activity 1.10 Are bases also salts? Are acids also salts?