Question

how many electrons should be added to the reactant side?
?e⁻ + 8h⁺ + mno₄⁻ → mn²⁺ + 4h₂o

Explanation:

Step1: Determine oxidation states of Mn

In \(MnO_4^-\), let oxidation state of Mn be \(x\). Oxygen is -2, so \(x + 4(-2)= -1\) → \(x - 8 = -1\) → \(x = +7\). In \(Mn^{2+}\), oxidation state is +2.

Step2: Calculate electron change

Mn goes from +7 to +2, so each Mn gains \(7 - 2 = 5\) electrons. Since there's 1 Mn atom, total electrons needed are 5.

Answer:

5