Question

$20 \,mL$ of $0.02\, M\, K _2 Cr _2 O _7$ solution is used for the titration of $10\, mL$ of $Fe ^{2+}$ solution in the acidic medium.
The molarity of $Fe ^{2+}$ solution is_____ $\times 10^{-2} M$. (Nearest Integer)

Answer 1

Eq. of $K _2 Cr _2 O _7=$ Eq. of $Fe ^{2+}$
$\Rightarrow \left(\text { Molarity } \times \text { volume } \times \text { n.f) of } K _2 Cr _2 O _7\right. $
$ =(\text { molarity } \times \text { volume } \times \text { n.f }) \text { of } Fe ^{2+} $
$\Rightarrow 0.02 \times 20 \times 6= M \times 10 \times 1 $
$\Rightarrow M =0.24 $
$\Rightarrow \text { Molarity }=24 \times 10^{-2}$