Use Fe = 56, S = 32, O = 16. A 5.00 g sample containing FeSO4 and inert impurity is dissolved in dilute acid and titrated with 0.100 M K2Cr2O7 (Cr2O7^2- -> 2Cr^3+); 24.0 mL is required. Find the mass percentage of FeSO4 (two decimals).

JEE Main levelNumerical answerDifficulty 2 of 3rx136

Use Fe = 56, S = 32, O = 16. A $5.00 g$ sample containing $FeSO X_{4}$ and inert impurity is dissolved in dilute acid and titrated with $0.100 M$ $K X_{2} Cr X_{2} O X_{7}$ ( $Cr X_{2} O X_{7} X^{2 -} 2 Cr X^{3 +}$ ); $24.0 mL$ is required. Find the mass percentage of $FeSO X_{4}$ (two decimals).

Numerical answer type, answer in %, tolerance 0.05.

K X_{2} Cr X_{2} O X_{7}

24.0 \times 0.100 = 2.40

mmol,

n = 6

, so

Fe X^{2 +}

= 14.4

mmol. Mass

= 14.4 \times 1 0^{- 3} \times 152 = 2.1888 g

. Percentage

= 2.1888/5.00 \times 100 = 43.78%