Question

Which gas is usually liberated when an acid reacts with a metal? Illustrate with an example. How will you test for the presence of this gas?

Answer 1

When an acid react with a metal, it liberates hydrogen gas. 

For example: 

Zn(s) + 2HCl(aq.) → ZnCl₂(aq.) + H₂(g) 

To test the presence of H₂ gas, bring a burning splinter near the mouth of the test tube where H₂ gas is released, the splinter burns with a pop sound.

Answer 2

Hydrogen gas is usually liberated when an acid reacts with metal .

Eg .  Na (s) +  HCL(aq)  ---->  NaCl (aq) + H₂ (g)