In the standardisation of N a2 S2 O3 using K2 C r2 O7 by iodometry, the equivalent weight of K2 C r2 O7 is

Question

In the standardisation of N a2 S2 O3 using K2 C r2 O7 by iodometry, the equivalent weight of K2 C r2 O7 is (A) ( text molecular weight /2) (B) ( text molecular weight /6) (C) ( text molecular weight /3) (D) same as molecular weight

Tardigrade Admin · Accepted Answer

Cr 2 O 72-+14 H ++6 e- arrow 2 Cr 3++7 H 2 O 6 I - arrow 3 I 2+6 e- 2 Na 2 S 2 O 3+ I 2 arrow Na 2 S 4 O 6+2 NaI In this reaction, Eq. wt. of K 2 Cr 2 O 7=( text Molecular weight /3 × 2) =( text Molecular weight /6)

Q. In the standardisation of $N a_{2} S_{2} O_{3}$ using $K_{2} C r_{2} O_{7}$ by iodometry, the equivalent weight of $K_{2} C r_{2} O_{7}$ is

$\frac{molecular weight}{2}$

$\frac{molecular weight}{6}$

$\frac{molecular weight}{3}$

same as molecular weight

$C r_{2} O_{7}^{2 -} + 14 H^{+} + 6 e^{-} \to 2 C r^{3 +} + 7 H_{2} O 6 I^{-} \to 3 I_{2} + 6 e^{-}$
$2 N a_{2} S_{2} O_{3} + I_{2} \to N a_{2} S_{4} O_{6} + 2 N a I$
In this reaction, Eq. wt. of
$K_{2} C r_{2} O_{7} = \frac{Molecular weight}{3 \times 2}$
$= \frac{Molecular weight}{6}$

Q. In the standardisation of Na2​S2​O3​ using K2​Cr2​O7​ by iodometry, the equivalent weight of K2​Cr2​O7​ is

2 molecular weight ​

6 molecular weight ​

3 molecular weight ​