Question

How many moles of $KMnO_{4}$ are needed to oxidise a mixture of 1 mole each of $FeSO_{4}$ and $FeC_{2}O_{4}$ in acidic medium?

• A. 4/5
• B. 5/4
• C. 3/4
• D. 5/3

Answer 1

Answer: (A)

$\text{n}\text{o}. \, \text{o}\text{f} \, \text{e}\text{q}\text{u}\text{i}\text{v}\text{a}\text{l}\text{e}\text{n}\text{t}\text{s} \, = \, \text{m}\text{o}\text{l}\text{e}\text{s} \, \times \text{n-}\text{f}\text{a}\text{c}\text{t}\text{o}\text{r}$

$\text{n-factor} \, \text{of} \, \left(\text{KMnO}\right)_{4} = 5 \text{(in} \, \text{acidic} \, \text{medium)}$

$\text{F}\text{e}\text{S}\text{O}_{4}=1$

$\text{F}\text{e}\text{C}_{2}\text{O}_{4}=3$

Number of equivalents of $KMnO_{4}$

= Number of equilvanets of $FeSO_{4}+$ Number of equivalents of $FeC_{2}O_{4}$

$x\times 5=1\times 1+1\times 3$

$x=\frac{4}{5}$