Reaction of HNO3 with metals generally dose not evolve H2 gas?

Question

PLZ SND SOON

Answer 1

It depends on the metal. If the metal is below hydrogen in the reactivity series, then the oxidising agent is the nitrate ion, and the hydrogen is not released, but combines to form water. An example is the reaction with copper.

3Cu + 8HNO3 → 3Cu(NO3)2 + 2NO + 4H2O

Otherwise, the soluble metal nitrate forms, and hydrogen is released.

2Na + 2HNO3 → 2NaNO3 + H2

Answer 2

Actually

It depends on the metal. If the metal is below hydrogen in the reactivity series, then the oxidising agent is the nitrate ion, and the hydrogen is not released, but combines to form water. An example is the reaction with copper.

3Cu + 8HNO3 → 3Cu(NO3)2 + 2NO + 4H2O

Otherwise, the soluble metal nitrate forms, and hydrogen is released.

2Na + 2HNO3 → 2NaNO3 + H2

Answer 3

Since HNO3 is a powerful oxidizing agent, any hydrogen formed is oxidized before it can escape.

Very dilute HNO3 with metals can form some hydrogen.

These reactions are complex and depend on dilution, temperature and metal. Moderately dilute, room temperature with copper forms nitric oxide, NO.  Concentrated HNO3 with copper there is more formation of nitrogen peroxide, NO2, together with NO.

Nitric acid is produced in iron retorts by distillation of sulfuric acid and sodium nitrate, leaving NaHSO4.  If there is more NaNO3 left and addtional heat is applied the NaHSO4 will react with the NaNO3 to make more HNO3, but the higher temperatures will decompose the HNO3.

Less HNO3 is needed to dissolve the same amount of metal if it is more dilute.

Answer 4

yes! It's an oxidizing acid and generally gives N-O derivatives.