A 0.4250 g sample containing sodium oxalate (Na2C2O4, molar mass 134) and inert matter is dissolved, acidified and titrated at 60-70 degC with 0.0200 M KMnO4; 24.30 mL is required. Find the percentage of Na2C2O4 in the sample (two decimals).

JEE Main levelNumerical answerDifficulty 2 of 3eq192

A $0.4250 g$ sample containing sodium oxalate ( $Na X_{2} C X_{2} O X_{4}$ , molar mass $134$ ) and inert matter is dissolved, acidified and titrated at $60 - 7 0^{\circ} C$ with $0.0200 M$ $KMnO X_{4}$ ; $24.30 mL$ is required. Find the percentage of $Na X_{2} C X_{2} O X_{4}$ in the sample (two decimals).

Numerical answer type, answer in %, tolerance 0.05.

Mmol of

KMnO X_{4}

= 24.30 \times 0.0200 = 0.486

; oxalate

= 0.486 \times 5/2 = 1.215

mmol. Mass

= 1.215 \times 134 = 162.8

mg. Percentage

= 162.8/425.0 \times 100 = 38.31%