(a) What happens when an acid reacts with a metal? Give chemical equation of the reaction involved.
(b) Which gas is usually liberated when an acid reacts with a metal? How will you test for the presence of this gas?
(a) When an acid reacts with a metal, then a salt and hydrogen gas are formed.
Zn(s) + 2HCl → ZnCl2 + H2(g)
(b) Hydrogen gas is liberated when an acid reacts with a metal. When reaction between an acid and a metal occurs, we observe formation of gas bubbles. When these gas bubbles are passed through soap solution, gas filled soap bubbles rise into the air. When a burning candle is brought near a gas-filled soap bubble, the gas present in the soap-bubble burns with a ‘pop’ sound. Only hydrogen gas burns making a ‘pop’ sound. This shows that hydrogen gas is evolved in the process.