Question

Balance occuring in acidic solution and then as if they were occuring in a basic solution

PbO2(s) +Ba(s) --> Pb2+ (aq)+Ba2+ (aq)

Answer 1

1)
Pb in PbO2 has oxidation state of +4
Pb in Pb+2 has oxidation state of +2
So, Pb in PbO2 is reduced to Pb+2

Ba in Ba has oxidation state of 0
Ba in Ba+2 has oxidation state of +2
So, Ba in Ba is oxidised to Ba+2





Reduction half cell:
PbO2 + 2e- --> Pb+2
Oxidation half cell:
Ba --> Ba+2 + 2e-
Number of electrons is same in both half reactions.
So, balancing of electrons is not required. It's already balanced

Lets combine both the reactions.
PbO2 + Ba --> Pb+2 + Ba+2
Balance Oxygen by adding water

PbO2 + Ba --> Pb+2 + Ba+2 + 2 H2O

Balance Hydrogen by adding H+
PbO2 + Ba + 4 H+ --> Pb+2 + Ba+2 + 2 H2O

This is balanced chemical equation in acidic medium
Answer:
PbO₂(s) + Ba(s) + 4 H⁺(aq) --> Pb²⁺(aq) + Ba²⁺(aq) + 2 H₂O(l)

2)
Add equal number of OH- on both sides as the number of H+
PbO2 + Ba + 4 H+ + 4 OH- --> Pb+2 + Ba+2 + 2 H2O + 4 OH-

Combine H+ and OH- to form water
PbO2 + Ba + 4 H2O --> Pb+2 + Ba+2 + 2 H2O + 4 OH-

Remove common H2O from both sides
Balanced Eqn is
PbO2 + Ba + 2 H2O --> Pb+2 + Ba+2 + 4 OH-
This is balanced chemical equation in basic medium
Answer:
PbO₂(s) + Ba (s) + 2 H₂O (l) --> Pb²⁺ (aq) + Ba²⁺(aq) + 4 OH^-(aq)