Question

When the following equation is balanced properly under basic conditions, what are the coefficients of the species shown? 8,0,2- + CIO Water appears in the balanced equation as a reactant, product, neither) with a coefficient of (Enter 0 for neither.) How many electrons are transferred in this reaction?

Answer 1

S in S2O3-2 has oxidation state of +2
S in SO3-2 has oxidation state of +4
So, S in S2O3-2 is oxidised to SO3-2

Cl in ClO4- has oxidation state of +7
Cl in ClO3- has oxidation state of +5
So, Cl in ClO4- is reduced to ClO3-





Reduction half cell:
ClO4- + 2e- --> ClO3-
Oxidation half cell:
S2O3-2 --> 2 SO3-2 + 4e-
Balance number of electrons to be same in both half reactions

Reduction half cell:
2 ClO4- + 4e- --> 2 ClO3-
Oxidation half cell:
S2O3-2 --> 2 SO3-2 + 4e-

So, 4 electrons are transferred

Lets combine both the reactions.
2 ClO4- + S2O3-2 --> 2 ClO3- + 2 SO3-2
Balance Oxygen by adding water

2 ClO4- + S2O3-2 + H2O --> 2 ClO3- + 2 SO3-2

Balance Hydrogen by adding H+
2 ClO4- + S2O3-2 + H2O --> 2 ClO3- + 2 SO3-2 + 2 H+

Add equal number of OH- on both sides as the number of H+
2 ClO4- + S2O3-2 + H2O + 2 OH- --> 2 ClO3- + 2 SO3-2 + 2 H+ + 2 OH-

Combine H+ and OH- to form water
2 ClO4- + S2O3-2 + H2O + 2 OH- --> 2 ClO3- + 2 SO3-2 + 2 H2O

Remove common H2O from both sides
Balanced Eqn is
S2O3-2 + 2 ClO4- + 2 OH- --> 2 ClO3- + 2 SO3-2 + H2O
This is balanced chemical equation in basic medium

Answer:
1, 2, 2, 2
Water appear as product with coefficient 1
4 electrons are transferred