Question

balance by oxidation number method​

Answer 1

Answer:

Separate the redox reaction into half-reactions. A redox reaction is nothing but both oxidation and reduction reactions taking place simultaneously.

a) Assign oxidation numbers for each atom in the equation. Oxidation number (also called oxidation state) is a measure of the degree of oxidation of an atom in a substance (see: Rules for assigning oxidation numbers).

Mn+7O-24- + Br-1- → Mn+4O-22 + Br+5O-23- + O-2H+1-

b) Identify and write out all redox couples in reaction. Identify which reactants are being oxidized (the oxidation number increases when it reacts) and which are being reduced (the oxidation number goes down).

O:Br-1- → Br+5O-23-(Br)

R:Mn+7O-24- → Mn+4O-22(Mn)

c) Combine these redox couples into two half-reactions: one for the oxidation, and one for the reduction (see: Divide the redox reaction into two half-reactions).

O:Br-1- → Br+5O-23-

R:Mn+7O-24- → Mn+4O-22

2MnO4- + Br- + H2O → 2MnO2 + BrO3- + 2OH-