JEE Mains · Chemistry · STD 12 - 2. Electrochemistry
Consider the electrochemical cell:
Pt | \(O_{2}\)(g) (1 bar) | HCl (aq) || \(M^{2+}\) (aq, 1.0 M) | M(s). The pH above which, oxygen gas would start to evolve at anode is _______ (nearest integer).
\(\left[\begin{array}{ll}\text { Given : } \left.\begin{array}{l} E _{ M ^{2+} / M }^0=0.994 V \\ E _{ O _2 / H _2 O }^0=1.23 V\end{array}\right\} \\ \text { standard reduction potential } \\ \text { and } \frac{ RT }{ F }(2.303)=0.059 V \text { at the given condition }\end{array}\right]\)
- A 2
- B 4
- C 6
- D 8
Answer & Solution
Correct Answer
(B) 4
Step-by-step Solution
Detailed explanation
For spontaneity \(E_{cell} > 0\). At limiting condition: \(E_{oxi}(anode) = -E_{red}(cathode)\) \(H_{2}O \rightarrow 2H^{+} + \frac{1}{2}O_{2} + 2e^{-}\) \(E = E ^{\circ}-\frac{0.059}{2} \log \left[\frac{\left[ H ^{+}\right]^2 \times P _{ O _2}^{1 / 2}}{1}\right]\)…
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