1.390 g of a sample of impure ferrous sulphate heptahydrate, FeSO4.7H2O (molar mass 278, Fe = 56), is dissolved in dilute H2SO4 and titrated with 0.0400 M KMnO4, needing 24.0 mL. Impurities do not react. Which of the following are correct?

The sample contains 4.80 mmol of Fe^2+

The sample contains 268.8 mg of iron(II)

The sample contains 4.80 mmol of Fe^2+

The sample contains 268.8 mg of iron(II)

The titration consumes 4.80 mmol of KMnO4

JEE Advanced levelOne or more correct optionsDifficulty 3 of 3rx218

1.390 g of a sample of impure ferrous sulphate heptahydrate, $FeSO X_{4} \cdot 7 H X_{2} O$ (molar mass 278, Fe = 56), is dissolved in dilute $H X_{2} SO X_{4}$ and titrated with 0.0400 M $KMnO X_{4}$ , needing 24.0 mL. Impurities do not react. Which of the following are correct?

mmol

KMnO X_{4}

24.0 \times 0.0400 = 0.960

(so D is wrong);

Fe X^{2 +}

0.960 \times 5 = 4.80

mmol. Mass of

FeSO X_{4} \cdot 7 H X_{2} O

4.80 \times 278 = 1334.4

mg, which is 1334.4/1390 x 100 = 96.0%. Mass of Fe =

4.80 \times 56 = 268.8

mg. A, B and C are correct.