Question

Hydrogen gas is not evolved when metals react with nitric acid.Give reason?

Answer 1

See the explanation

Explanation:

When metals react with nitric acid hydrogen gas is liberated.

Nitric acid is a very strong oxidizing agent.

So , it oxidizes the hydrogen gas formed during the reaction to form water and an oxide of nitrogen (`NO , N_2O , NO_2" etc."`).

The reaction for it is:-

`Zn + 4HNO_3 -> Zn(NO_3)_2 + 2NO_2 + 2H_2O`

Exception:-
Magnesium and manganese react with very dilute nitric acid to liberate hydrogen gas.

The reaction for it is:-

`Mg + 2HNO_3 -> Mg(NO_3)_2 + H_2`

Answer 2

Because nitric acid is a powerful oxidising agent and can oxidize hydrogen gas to water

Explanation:

Because it oxidises hydrogen gas to water.

Answer 3

Because nitric acid has a complex redox manifold....

Explanation:

Depending on conditions, nitric acid may be reduced to give nitrogen oxides rather than dihydrogen....

Copper reacts with dilute nitric acid to give copper nitrate and `NO`:

`3Cu(s) + 8HNO_3(aq) rarr 3Cu^(2+) + 2NO(g) + 6NO_3^− + 4 H_2O`