What must be done to the following half-reactions before they can be added together?
Mn (s) → Mn ²⁺(aq) + 2e^-
Fe ³⁺ (aq) + 3 e^- → Fe (s)

Question

What must be done to the following half-reactions before they can be added together? Mn (s)→ Mn ²⁺(aq)+ 2e^- Fe ³⁺ (aq)+ 3 e^- → Fe (s)

Quizplus · Accepted Answer

The half-reactions need to be balanced in terms of the number of electrons transferred and the number of atoms present on the reactant and product sides.

To balance the Mn half-reaction, it needs to be tripled:

3 Mn (s) → 3 Mn^2+ (aq) + 6 e^-

To balance the Fe half-reaction, it needs to be doubled:

2 Fe^3+ (aq) + 6 e^- → 2 Fe (s)

Now, the two half-reactions can be added together:

3 Mn (s) + 2 Fe^3+ (aq) → 3 Mn^2+ (aq) + 2 Fe (s)

What Must Be Done to the Following Half-Reactions Before They