Summary of acid and base reaction with metals
As you all know acids are substances that have a pH below 7, while bases are substances with a pH above 7. We can identify whether a substance is acidic or basic with the help of various indicators. Today we will see how these acids and bases react with metals.
Reaction of acid with metals
When an acid reacts with a metal, this results in the formation of a salt with the evolution of hydrogen gas.
Acid + Metal → Salt + Hydrogen gas
 HCl(aq)  + Zn(s) → ZnCl2(aq) + H2(g)
Here hydrochloric acid reacts with metal Zinc(Zn) to give ZnCl2 as salt and hydrogen gas. The Zn metal displaces the hydrogen in this reaction.
Reaction of base with metals
When a base reacts with a metal, this results in the formation of a salt with the evolution of hydrogen gas.
Base + Metal  → Salt + Hydrogen gas
2NaOH(aq)+ Zn(s) → Na2ZnO2(s) + H2(g)
In the above reaction Sodium hydroxide(NaOH), a base reacts with a metal Zinc(Zn) to give a salt, sodium zincate(Na2ZnO2), and hydrogen gas as the product.
We can conclude that when an acid or base reacts with a metal, hydrogen gas is produced, and salt is formed as a result.