Balance the equation by half reaction method:
1. Write the oxidation and reduction half-reactions by observing the changes in oxidation numbers and write these separately.
Oxidation half-reaction:
Reduction half-reaction:
2. Balancing the oxidation half reaction.
(i) The balance I atoms are done by multiplying HIO3 by 2.
0 +5
(ii) Add 10 electrons towards R.H.S. in order to balance the changes on iodine atoms.
(iii) Balance the O atoms by adding six H2O molecules towards L.H.S.
(iv) Balance H atoms by adding ten H+ towards
R.H.S.
3. Balancing the reduction half reaction.
(i) Balancing of N is not required as the number of each N is one on both the sides.
+5 +4
HNO3 NO2
(ii) Add one electron towards L.H.S. in order to balance the charges on the nitrogen atom.
+5 +4
HNO3 + e- NO2
(iii) Balance O atoms by adding one H2O molecule towards R.H.S.
5 4
HNO3 + e- NO2 + H2O
(iv) Balance H atoms by adding one H+ towards
L.H.S.
+5 +4
HNO3 + H+ + e- NO2 + H2O
(Balance reduction half reaction)
4. Multiply balanced reduction half-reaction by 10 to equate electrons and add both the half reactions.
This is a balanced redox reaction.
Balance the following equation by half reaction method in acidic medium: