Electrochemical Potentials, Free Energy, Equilibrium, and Concentration Cells

All flashcards

How are standard free energy change and standard cell potential related?

$\Delta G^\circ=-nFE^\circ_{\text{cell}}$, where $n$ is the electron-transfer amount and $F$ is Faraday’s constant.

How are standard cell potential and equilibrium constant related at 298.15 K?

$E^\circ_{\text{cell}}=(0.0592\ \text{V}/n)\log K$.

What is the Nernst equation at 298.15 K?

$E_{\text{cell}}=E^\circ_{\text{cell}}-(0.0592\ \text{V}/n)\log Q$.

How is the reaction quotient $Q$ constructed?

Divide product activities by reactant activities, raising each to its stoichiometric coefficient.

What creates the potential in a concentration cell?

A concentration difference between half-cells containing the same redox couple.

Quiz questions

1. Under specified nonstandard conditions, what does a positive cell potential indicate for the reaction as written?Answer: The forward reaction is spontaneous.
2. At equilibrium in an electrochemical cell, which condition holds?Answer: $Q=K$ and $E_{\text{cell}}=0$.
3. What is the standard cell potential of a concentration cell with identical redox couples in both half-cells?Answer: It is zero.
4. In a metal-ion concentration cell, which half-cell is generally the cathode?Answer: The half-cell with the more concentrated metal-ion solution.
5. Which substances are omitted when constructing a reaction quotient?Answer: Pure solids and pure liquids.