JEE Main 2023 · Chemistry · Redox Reactions and Titrations · medium

A 25.0 mL sample of a hydrogen peroxide solution requires 20.0 mL of 0.500 M KMnO4 for complete reaction in acidic medium. The strength of the…

Numerical answer

25.0\ \mathrm{mL}

sample of a hydrogen peroxide solution requires

20.0\ \mathrm{mL}

0.500\ \mathrm M

\mathrm{KMnO_4}

for complete reaction in acidic medium. The strength of the solution in

\mathrm{g\,L^{-1}}

is (molar mass of

\mathrm{H_2O_2}=34\ \mathrm{g\,mol^{-1}}

)

Show answer and solution

Answer: 34

2\mathrm{MnO_4^-}+5\mathrm{H_2O_2}+6\mathrm{H^+}\to2\mathrm{Mn^{2+}}+5\mathrm{O_2}+8\mathrm{H_2O}

. Moles of

\mathrm{KMnO_4}=20\times0.5=10

mmol, so

\mathrm{H_2O_2}=10\times\frac52=25

mmol in

25

mL, i.e.

1.0\ \mathrm M

. Strength

=1.0\times34=34\ \mathrm{g\,L^{-1}}

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