Homework
Textbook assignment: Read Kotz and Triechel, Chemistry and Chemical Reactivity Chapter 18: Sections 5 to 8.
The half-cell voltages listed in the previous section are determined under standard conditions. We can consider electric potentials using the Nernst equation for temperatures and concentrations when the latter are expressed in the reaction quotient Q.
Principle | Formula | Notes |
---|---|---|
Work | w_{max} = nFE | E: cell potential nF: amount of electric charge transfered |
Nernst Equation | $$E\text{}=\text{}E\text{\xb0}-\text{}(\frac{\mathrm{RT}}{\mathrm{nF}})\text{}\mathrm{ln}\text{}Q$$ | E: actual potential at temperature T E°: potential at STP n: number of moles of electrons transfered F: total charge per mole electrons R: gas constant T: Temperature (K) Q: reaction quotient |
Nernst at STP (298.15K) | $$\begin{array}{l}E\text{}=\text{}E\text{\xb0}-\text{}(\frac{\mathrm{RT}}{F})\frac{1}{n}\text{}\mathrm{ln}\text{}Q\text{}\\ E=E\text{\xb0}-\text{}\frac{0.0257}{n}\text{}\mathrm{ln}\text{}Q\text{}\end{array}$$ | Constants R, T, F calculated |
Free Energy (STP) | Δ_{r}G° = -nFE° | G°: Gibbs free energy for reduction half-reaction E°: electric potential change for reduction half-reaction |
Free Energy and Nernst at Equilibrium | $$\begin{array}{l}E\text{\xb0}=\text{}\frac{0.0257}{n}\text{}\mathrm{ln}\text{}K\text{}\\ \mathrm{ln}\text{}K\text{}=\text{}\frac{\mathrm{nE}\text{\xb0}}{0.0257}\end{array}$$ | E = 0 at equilibrium |
Electron count | $$i\text{}=\frac{C}{t}\text{}$$ | i: current (Amps) C: charge t: time |
Read the following weblecture before chat: Electrochemistry and Thermodynamics
Review the Videos at Thinkwell Video Lessons.
Use the Electrolysis Experiment simulation to run a virtual electrolysis experiment.
Use your batteries (or commercial batteries) to observe the results of electrolysis on common molecules and rank results. Write and post your formal report.
Resources:
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