Chemical Properties of HNO3

XII CHEMISTRYSidra Javed

Chemical properties of HNO3 are of 3 types

1. Acidic properties

2. Nitrating properties

3. Oxidizing properties

Acidic properties of HNO3

● HNO3 is a strong monobasic/monoprotic acid i.e. provide

only 1 H+ ion

HNO3 + H2O → H3O+ + NO3

-

● Neutralizes alkalis/bases to give salt and water

HNO3 + NaOH → NaNO3 + H2O

Nitrating properties of HNO3

● HNO3 is a good nitrating agent

● When HNO3 vapors are passed through Methane at 450oC in presence

of copper, nitromethane is formed.

CH4 + HNO3 CH3NO2 + H2OCu

450oC

Nitrating properties of HNO3:

● Nitration of Benzene in presence of H2SO4:

Oxidising properties of HNO3:

● HNO3 is a strong oxidising agent

● Oxidation State of N changes from N+5 to N-3

● Degree of oxidation depends upon:

○ Concentration of acid

■ Lower concentration of acid → Greater oxidation

○ Nature of element

■ Highly reactive element → Greater oxidation

Reaction with Cu metal

● Concentrated HNO3 reduces to NO2

Cu + 4HNO3 (conc) → Cu(NO3)2 + 2NO2 + 2H2O

Reaction with Cu metal

● Dilute HNO3 reduces to NO

3Cu + 8HNO3 (dil) → 3Cu(NO3)2 + 2NO + 4H2O

Reaction with Mg (more reactive metal)

● Dilute HNO3 reduces to N2O

4Mg + 10HNO3 → 4Mg(NO3)2 + N2O +

5H2O

Reaction with Zn (More reactive metal)

● Very dilute HNO3 reduces to NH4NO3

4Zn + 10HNO3 → 4Zn(NO3)2 + NH4NO3 + 3H2O

Reactions with Nonmetals

● HNO3 oxidizes nonmetals and reduces to NO2

S + 6HNO3 → H2SO4 + 6NO2 + 2H2O

P + 5HNO3 → H3PO4 + 5NO2 + H2O

Si + 4HNO3 → SiO2 + 4NO2 + 2H2O

Importance & Uses of HNO3

Fertilizers

NH4NO3 , NaNO3 etc

ExplosivesNitro glycerine

ExplosivesDynamite