Q. What are the Chemical Properties of Nitric Acid?

Ans.

Reactions as an acid: Nitric acid ionizes well because it is a strong acid.

HNO₃ --> H⁺ + NO3^-

It turns blue litmus red, indicating that it is an acid. The acidic proton (H⁺) produced by the nitric acid can react with metal oxides (such as CuO) and carbonates (such as ZnCO₃):

2H⁺ + CuO --> Cu₂+ + H₂O

2H⁺ + ZnCO₃ --> Zn₂+ + CO₂ + H₂O

Reactions as an oxidizing agent: Nitric acid is a powerful oxidizing agent. The nitrogen in the nitrate ion becomes reduced.

Nitric acid oxidizes carbon to form an oxide. For example, glowing splints that are producing carbon will burst into flame when lowered into a watch glass containing nitric acid. Carbon dioxide and brown fumes of nitrogen dioxide are given off.

C + 4HNO₃ --> CO₂ + 4NO₂ + 2H₂O

Nitric acid will oxidize sulfur to form sulfuric acid.

S + 6HNO₃ --> H₂SO₄ + 6NO₂ + 2H₂O

Notice that the S has been oxidized from 0 to +6 and that the N has been reduced from +5 to +4.