Mohr's Salt vs $$\text{KMnO}_4$$

Formula / Core Reaction:

$$\text{MnO}_4^- + 5\text{Fe}^{2+} + 8\text{H}^+ \rightarrow \text{Mn}^{2+} + 5\text{Fe}^{3+} + 4\text{H}_2\text{O}$$

Concept: Permanganate quantitatively oxidizes ferrous ions ($\text{Fe}^{2+}$) from Mohr's salt to ferric ions ($\text{Fe}^{3+}$) in acidic medium ($\text{H}_2\text{SO}_4$) at room temperature.

Notation / Key Observation:

• n-factor of $$\text{KMnO}_4 = 5$$;
• n-factor of Mohr's salt $$[\text{FeSO}_4\cdot(\text{NH}_4)_2\text{SO}_4\cdot 6\text{H}_2\text{O}] = 1$$ ($$\text{Fe}^{+2} \rightarrow \text{Fe}^{+3}$$);
• Equivalence relation: $$5 \cdot M_{\text{KMnO}_4} \cdot V_{\text{KMnO}_4} = 1 \cdot M_{\text{Mohr}} \cdot V_{\text{Mohr}}$$.