Question

When the following oxidation

Answer 1

0          +2                +1          0

Rb(s) + Cu²⁺(aq) Rb⁺(aq) + Cu(s)

Oxidation half reaction : Rb(s) Rb⁺(aq)

Reduction half reaction : Cu²⁺(aq) Cu(s)

Balancing oxidation half reaction : Rb(s) Rb⁺(aq)

Balancing charge ( by adding electrons ) : Rb(s) Rb⁺(aq) + e^-        ---------------(1)

Balancing oxidation half reaction : Cu²⁺(aq) Cu(s)

Balancing charge ( by adding electrons ) : Cu²⁺(aq) + 2e^- Cu(s)     ---------------(2)

Add both the equations (1) & (2) so that the electrons on both sides will cancel each other.

This can be done by [2xEqn(1) ] + Eqn (2) gives

2Rb(s) + Cu²⁺(aq) + 2e^- 2Rb⁺(aq) + 2e^- + Cu(s)

2Rb(s) + Cu²⁺(aq)   2Rb⁺(aq) + Cu(s)

This is the balanced equation.

So the lowest whole-number coefficient for Rb⁺(aq) is 2.