Use Fe = 56, O = 16. Fe3O4 (an oxide containing Fe^2+ and Fe^3+) is dissolved in dilute acid, and only its Fe^2+ is oxidised by acidified KMnO4 (to Mn^2+). Find the volume in mL (nearest integer) of 0.02 M KMnO4 needed for 2.32 g of Fe3O4.

JEE Main levelNumerical answerDifficulty 2 of 3rx138

Use Fe = 56, O = 16. $Fe X_{3} O X_{4}$ (an oxide containing $Fe X^{2 +}$ and $Fe X^{3 +}$ ) is dissolved in dilute acid, and only its $Fe X^{2 +}$ is oxidised by acidified $KMnO X_{4}$ (to $Mn X^{2 +}$ ). Find the volume in mL (nearest integer) of $0.02 M$ $KMnO X_{4}$ needed for $2.32 g$ of $Fe X_{3} O X_{4}$ .

Numerical answer type, answer in mL, tolerance 0.5.

Fe X_{3} O X_{4}

FeO \cdot Fe X_{2} O X_{3}

has one

Fe X^{2 +}

per formula unit, so

n = 1

M = 232

, moles

= 0.01

, equivalents

= 0.01

N (KMnO X_{4}) = 0.1

, so

V = 0.01/0.1 = 0.1 L = 100 mL