1. Tardigrade
  2. Question
  3. Chemistry
  4. An impure sample of sodium oxalate (Na2C2O4) weighing 0.20 g is dissolved in aqueous solution of H2SO4 and solution is titrated at 70°C, requiring 45 mL of 0.02 M KMnO4 solution. The end point is overrun, and back titration in carried out with 10 mL of 0.1 M oxalic acid solution. Find the percentage purity of Na2C2O4 in sample.

Question Error Report

Thank you for reporting, we will resolve it shortly

Back to Question

Q. An impure sample of sodium oxalate $(Na_2C_2O_4)$ weighing $0.20 \,g$ is dissolved in aqueous solution of $H_2SO_4$ and solution is titrated at $70^{\circ}C$, requiring $45\, mL$ of $0.02 \,M \,KMnO_4$ solution. The end point is overrun, and back titration in carried out with $10 \,mL$ of $0.1 \,M$ oxalic acid solution. Find the percentage purity of $Na_2C_2O_4$ in sample.

Some Basic Concepts of Chemistry

Solution:

$m$-eq. of $Na_2C_2O_4 = m$-eq. of $ KMnO_4$ reacted
total $m$-eq. of $KM nO_4^-$ excess $m$-eq. of $KMnO_4$ reacted with $H_2C_2O_ 4$
$= 45 \times 0.02 \times 5 -10 \times 0.1 \times 2 = 2.5$
$1000 \times \frac{W}{134} \times 2 = 2.5$
$W_{Na_2C_2O_4} = 0.1675\,g$
$\%$ purity of $Na_2C_2O_4$ in sample
$ = \frac{0.1675}{0.2} \times 100 = 83.75$