Name: Understanding Redox Titrations
Uploaded: 2019-07-19
Duration: 11 min 41 s
Description: Redox titration is a great way to identify whether a reaction is completed or not, where we know that reaction is complete, and it helps us find the strength...

Question

25 mL

of a solution containing

HCl

was treated with excess of

\frac{M}{5 {KIO}_{3}}

and

KI

solution of unknown concentration where

I_{2}

liberated is titrated against a standard solution of

0.021 M {Na}_{2} S_{2} O_{3}

solution whose

24 mL

were used up. Find the strength of

HCl

and volume of

{KIO}_{3}

solution consumed :

Accepted Answer

Given: $V_{HCl} = 25 mL, [{KIO}_{3}] = \frac{M}{5}, [{Na}_{2} S_{2} O_{3}] = 0.021 M$

First $HCl$ will react with ${KIO}_{3}$ to from ${KIO}_{3}$

$5 K \overset{+ 5}{I} O_{3} + 5 KI + 6 HCl \to_{}^{} 3 {\overset{0}{I}}_{2} + 6 KCl + 3 H_{2} O$

$n -$ factor of ${KIO}_{3}$ $= 5 - 0 = 5$

$n -$ factor of $I_{2} = \frac{(5 - 0)}{3} = \frac{5}{3}$

So here $m . eq$ of ${KIO}_{3} = m . eq$ of $I_{2}$

$m . eq = Normality \times volume$

Also $m . eq = Moles \times n - factor$

$\Rightarrow 5 \times \frac{1}{5} \times V_{{KIO}_{3}} = \frac{5}{3} \times n_{I_{2}}$ . . . . . . . . . . $(1)$

${\overset{0}{I}}_{2} + 2 {Na}_{2} {\overset{+ 2}{S}}_{2} O_{3} \to_{}^{} 2 Na \overset{- 1}{I} + {Na}_{2} {\overset{+ \frac{5}{2}}{S}}_{4} O_{6}$

$n -$ factor of $I_{2} = 2 (0 - (- 1)) = 2$

$n -$ factor of ${Na}_{2} {\overset{}{S}}_{2} O_{3}$ $= (\frac{5}{2} - 2) \times 2 = 1$

$m . eq$ of $I_{2} = m . eq$ of ${Na}_{2} {\overset{}{S}}_{2} O_{3}$

$\Rightarrow 2 \times n_{I_{2}} = 0.021 \times 1 \times 24$ . . . . . . . . . . . . . . $(2)$

By $(1) and (2)$

$V_{{KIO}_{3}} = 0.42 mL$

$m . eq of {KIO}_{3} = m . eq of HCl$

$\Rightarrow 5 \times \frac{1}{5} \times 0.42 = N \times 25$

$\Rightarrow N = 0.0168 N$

Hence, the Volume of ${KIO}_{3}$ consumed is $0.42 mL$ and strength of $HCl$ is $0.0168 N$

Important Questions on Redox Reactions

Learn and Prepare for any exam you want !

25 mL of a solution containing HCl was treated with excess of M5 KIO3 and KI solution of unknown concentration where I2 liberated is titrated against a standard solution of 0.021 M Na2 S2O3 solution whose 24 mL were used up. Find the strength of HCl and volume of KIO3 solution consumed :

Important Questions on Redox Reactions

Learn and Prepare for any exam you want !