Question

In a reaction, $C r_{2}O_{7}^{2 -}$ is reduced to $ \, C r^{3 +}$ . What will be the concentration of $0.1 \, M$ $K_{2}C r_{2}O_{7} \, $ in equivalent per litre?
$Cr_{2}O_{7}^{2 -}+14H^{+}+6e^{-} \rightarrow 2Cr^{3 +}+7H_{2}O$

• A. $0.9 \, N$
• B. $0.6 \, N$
• C. $0.3 \, N$
• D. $0.2 \, N$

Answer 1

Answer: (B)

$\text{N} = \text{M \times }$ Valence factor
$\because N= 0.1 \times 6\left(2 Cr_{}^{6 +} + 6 e^{-} \rightarrow 2 \left(Cr\right)^{3 +}\right)$
$K_{2}C r_{2}O_{7}= \, 0.6 \, N.$