NEET UG CHEMISTRY MCQ: ELECTRO CHEMISTRY

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Analyzing +4 | -1

Consider the reaction of extraction of gold from its ore:

\begin{aligned} & \mathrm{Au}(\mathrm{s})+2 \mathrm{CN}^{-}(\mathrm{aq})+\frac{1}{4} \mathrm{O}_2(\mathrm{g})+\frac{1}{2} \mathrm{H}_2 \mathrm{O}({l}) \rightarrow \mathrm{Au}(\mathrm{CN})_2{ }^{-}(\mathrm{aq})+\mathrm{OH}^{-}(\mathrm{aq}) \end{aligned}

Use the following data to calculate

\Delta G^{\circ}

for the above reaction.

\begin{aligned} & K_{\mathrm{f}}\left[\mathrm{Au}(\mathrm{CN})_2^{-}\right] =X \\ & \mathrm{O}_2+2 \mathrm{H}_2 \mathrm{O}+4 \mathrm{e}^{-} \rightarrow 4 \mathrm{OH}^{-} ; E^{\circ}=+0.41 \mathrm{~V} \\ & \mathrm{Au}^{3+}+3 \mathrm{e}^{-} \rightarrow \mathrm{Au} ; E^{\circ}=+1.50 \mathrm{~V} \\ & \mathrm{Au}^{3+}+2 \mathrm{e}^{-} \rightarrow \mathrm{Au}^{+} ; E^{\circ}=+1.40 \mathrm{~V} \end{aligned}

View answer and explanation

Correct option: A

-R T \ln X+1.29 \mathrm{~F}

Option A is correct because the overall reaction involves the formation of a complex ion and a redox reaction, and the Gibbs free energy change can be calculated using the given data.

NEET UG CHEMISTRY MCQ: ELECTRO CHEMISTRY

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