JEE MAIN - Chemistry (2024 - 5th April Evening Shift - No. 19)
For the electro chemical cell
$$\mathrm{M}\left|\mathrm{M}^{2+}\right||\mathrm{X}| \mathrm{X}^{2-}$$
If $$\mathrm{E}_{\left(\mathrm{M}^{2+} / \mathrm{M}\right)}^0=0.46 \mathrm{~V}$$ and $$\mathrm{E}_{\left(\mathrm{x} / \mathrm{x}^{2-}\right)}^0=0.34 \mathrm{~V}$$.
Which of the following is correct?
$$\mathrm{E}_{\mathrm{cell}}=0.80 \mathrm{~V}$$
$$\mathrm{M}+\mathrm{X} \rightarrow \mathrm{M}^{2+}+\mathrm{X}^{2-}$$ is a spontaneous reaction
$$\mathrm{E}_{\text {cell }}=-0.80 \mathrm{~V}$$
$$\mathrm{M}^{2+}+\mathrm{X}^{2-} \rightarrow \mathrm{M}+\mathrm{X}$$ is a spontaneous reaction
Explanation
$$\begin{aligned} & \mathrm{E}_{\mathrm{cell}}^{\circ}=\mathrm{E}_{\mathrm{X} \mid \mathrm{X}^{2-}}^{\circ}-\mathrm{E}_{\mathrm{M}^{2+} \mid \mathrm{M}}^{\circ} \\ & =0.34-0.46 \\ & =-0.12 \mathrm{~V} \text { (Non-spontaneous) } \end{aligned}$$
So, reverse reaction will be spontaneous.
$$\mathrm{M}^{2+}+\mathrm{X}^{2-} \rightarrow \mathrm{M}+\mathrm{X}$$
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