Question

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. $5$
• D. $6$

Answer 1

The correct option is D $6$

$C{r}_2{O}_7^{2-}+$ $Fe$ ${}^{2+}\to$ $Fe$ ${}^{3+}+Cr$ ${}^{3+}$

$n$ factor of $C{r}_2{O}_7^{2-}=6$

$n$ factor of $F{e}^{2+}=1$

So, to reduce one mole of dichromate, $6$ moles of $F{e}^{2+}$ are required.

Hence, the correct option is $D$