1. 10⁻¹⁴ atm 2. 10⁻¹² atm 3. 10⁻¹⁰ atm 4. 10⁻⁴ atm

Answer: 1. 10⁻¹⁴ atm Key idea: for the half cell 2H^++2e^-→ H₂ , the Nernst equation is E=0-0.059/2logfracP_(H_2)[H^+]² In pure water [H^+]=10⁻⁷ M. For E = 0, P_(H_2)=[H^+]²=(10⁻⁷)²=10⁻¹⁴ atm.

Topic: EMF, Nernst equation and applications· Redox Reactions and Electrochemistry

The pressure of H_2 required to make the potential of H_2 - electrode zero in pure water at 298 K is :

1. $10^{-14}$ atm

2. $10^{-12}$ atm

3. $10^{-10}$ atm

4. $10^{-4}$ atm

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Answer: 1. $10^{-14}$ atm

Key idea: for the half cell $\mathrm{2H^++2e^-\to H_2}$, the Nernst equation is

$$E=0-\frac{0.059}{2}\log\frac{P_{H_2}}{[H^+]^2}$$

In pure water $[H^+]=10^{-7}$ M. For E = 0, $P_{H_2}=[H^+]^2=(10^{-7})^2=10^{-14}$ atm.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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The pressure of H_2 required to make the potential of H_2 - electrode zero in pure water at 298 K is :

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