Verified Solution • 2025–26 Session moderate

QJEEM24Ch89fc: JEE Main 2024 Chemistry - Class 12 JEEM24Ch89fc Solution: Consider the following redox reaction : The standard reduction…

Consider the following redox reaction :

MnO4−+H++H2C2O4⇌Mn2++H2O+CO2\mathrm{MnO}_4^{-}+\mathrm{H}^{+}+\mathrm{H}_2 \mathrm{C}_2 \mathrm{O}_4 \rightleftharpoons \mathrm{Mn}^{2+}+\mathrm{H}_2 \mathrm{O}+\mathrm{CO}_2

The standard reduction potentials are given as below (Ered 0)\left(\mathrm{E}_{\text {red }}^0\right) :

amp;EMnO4−/Mn2+∘=+1.51 Vamp;ECO2/H2C2O4∘=−0.49 V\begin{aligned}& \mathrm{E}_{\mathrm{MnO}_4^{-} / \mathrm{Mn}^{2+}}^{\circ}=+1.51 \mathrm{~V} \\\\& \mathrm{E}_{\mathrm{CO}_2 / \mathrm{H}_2 \mathrm{C}_2 \mathrm{O}_4}^{\circ}=-0.49 \mathrm{~V}\end{aligned}

If the equilibrium constant of the above reaction is given as Keq=10x\mathrm{K}_{\mathrm{eq}}=10^x , then the value of x=x= __________ (nearest integer)

Step-by-Step Verified Solution

Cell Rxn;MnO4−+H2C2O4→Mn2++CO2\mathrm{Rx}^{\mathrm{n}} ; \mathrm{MnO}_4^{-}+\mathrm{H}_2 \mathrm{C}_2 \mathrm{O}_4 \rightarrow \mathrm{Mn}^{2+}+\mathrm{CO}_2

Ecell ∘=Eop ∘\mathrm{E}_{\text {cell }}^{\circ}=\mathrm{E}_{\text {op }}^{\circ} of anode +ERP∘+\mathrm{E}_{\mathrm{RP}}^{\circ} of cathode

=0.49+1.51=2.00 V=0.49+1.51=2.00 \mathrm{~V}

At equilibrium

Ecell =0, \mathrm{E}_{\text {cell }}=0 \text {, }

Ecell ∘=0.0591nlog⁡K\mathrm{E}_{\text {cell }}^{\circ}=\frac{0.0591}{\mathrm{n}} \log \mathrm{K}

2=0.059110log⁡K2=\frac{0.0591}{10} \log K

log⁡K=338\log K=338

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