MCQ
Consider a titration of potassium dichromate solution with acidified Mohr's salt solution using diphenylamine as indicator. The number of moles of Mohr's salt required per mole of dichromate is
- A$3$
- B$4$
- C$5$
- ✓$6$
✓
Answer
Correct option: D.
$6$
d
$\mathrm{Cr}_2 \mathrm{O}_7^{2-}+\mathrm{Fe}^{2+} \longrightarrow \mathrm{Fe}^{3+}+\mathrm{Cr}^{3+}$
$\mathrm{Cr}_2 \mathrm{O}_7^{2-}+\mathrm{Fe}^{2+} \longrightarrow \mathrm{Fe}^{3+}+\mathrm{Cr}^{3+}$
$\mathrm{n}$ factor of $\mathrm{Cr}_2 \mathrm{O}_7^{2-}=6$
$\mathrm{n}$ factor of $\mathrm{Fe}^{2+}=1$
So to reduce one mole of dichromate $6$ moles of $\mathrm{Fe}^{2+}$ are required.
Hence $(D)$ is correct.
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