Half reaction method of balancing redox reaction
CHCl3 + MnO4- = Cl2 + CO2 + Mn+2
The half-reaction method is a systematic approach used to balance redox reactions. Here's how you can balance the given equation using the half-reaction method:
Step 1: Split the equation into two half-reactions, one involving the reduction and the other involving the oxidation.
Reduction half-reaction: MnO4- → Mn2+
Oxidation half-reaction: CHCl3 → Cl2 + CO2
Step 2: Balance each half-reaction separately.
For the reduction half-reaction, the only atom that changes its oxidation state is manganese (Mn), going from +7 in MnO4- to +2 in Mn2+. To balance the number of electrons on each side, multiply the reduction half-reaction by 5:
5MnO4- → 5Mn2+ + ...
For the oxidation half-reaction, chlorine (Cl) goes from -1 in CHCl3 to 0 in Cl2. Carbon (C) goes from -4 in CHCl3 to +4 in CO2. To balance the number of chlorine atoms, multiply the oxidation half-reaction by 2:
2CHCl3 → Cl2 + 2CO2 + ...
Step 3: Combine the half-reactions and simplify.
Now, we need to balance the number of electrons between the two half-reactions. In this case, the reduction half-reaction has 5 electrons (5MnO4- → 5Mn2+ + ...), and the oxidation half-reaction has 10 electrons (2CHCl3 → Cl2 + 2CO2 + ...). To balance the electrons, multiply the reduction half-reaction by 2 and the oxidation half-reaction by 5:
10MnO4- + ... → 10Mn2+ + ...
10CHCl3 → 5Cl2 + 10CO2 + ...
Thus, the balanced overall redox reaction is:
10CHCl3 + 10MnO4- → 5Cl2 + 10CO2 + 10Mn2+ + ...