Magnetite, Fe3O4 (treat as one Fe^2+ and two Fe^3+), is oxidised completely to Fe2O3. How many moles of electrons are lost by 69.6 g of Fe3O4? (Fe 56, O 16.) Give two decimal places.

JEE Advanced levelNumerical answerDifficulty 3 of 3rx046

Magnetite, $Fe X_{3} O X_{4}$ (treat as one $Fe^{2 +}$ and two $Fe^{3 +}$ ), is oxidised completely to $Fe X_{2} O X_{3}$ . How many moles of electrons are lost by $69.6 g$ of $Fe X_{3} O X_{4}$ ? (Fe 56, O 16.) Give two decimal places.

Numerical answer type, answer in mol, tolerance 0.005.

Molar mass of

Fe X_{3} O X_{4} = 3 (56) + 4 (16) = 232 g/mol

. Moles

= 69.6/232 = 0.300

. Each formula unit has one

Fe^{2 +}

going to

Fe^{3 +}

, so

0.300

mol of electrons are lost.