Question

6 mol of a mixture of Mohr's salt and $F{e}_2{\left(S{O}_4\right)}_3$ requires 500 ml of 1 M of $K_{2}C{r}_2{O}_7$ for complete oxidation in acidic medium. The mole % of the Mohr's salt in the mixture is

• A. 75
• B. 50
• C. 60
• D. 25

Answer 1

Answer: (B)

$C{r}_2{O}_7^{2-}+6F{e}^{2+}(n=1)$ (Mohr's salt) $+14H^{+}\to 2C{r}^{3+}+6F{e}^{3+}+7H_{2}O$

Equivalent of $F{e}^{2+}=$ moles of Mohr's salt

$=$ equivalent of $K_{2}C{r}_2{O}_7$

$=500\times 10^{-3}\times 6\times 1=3$

Hence mole percent of Mohr's salt

$=\frac{3}{6}\times 100=50$