A 20.0 mL portion of an acidified FeSO4 solution required 28.4 mL of 0.0250 M K2Cr2O7 for complete oxidation of Fe^2+ to Fe^3+. Find the molarity of the FeSO4 solution (three decimals).

JEE Main levelNumerical answerDifficulty 2 of 3eq064

A $20.0 mL$ portion of an acidified $FeSO X_{4}$ solution required $28.4 mL$ of $0.0250 M$ $K X_{2} Cr X_{2} O X_{7}$ for complete oxidation of $Fe X^{2 +}$ to $Fe X^{3 +}$ . Find the molarity of the $FeSO X_{4}$ solution (three decimals).

Numerical answer type, answer in M, tolerance 0.001.

mol Cr2O7(2-) = 0.0284 x 0.0250 = 7.100e-04; mol Fe2+ = 6 x that = 4.260e-03. Molarity = 4.260e-03/0.0200 L = 0.213 M.