Work through the list without notes. If you cannot do a statement, follow its link, then come back. Guide = study guide; Practice = practice questions.
Understanding
- I can explain that E° is the cell potential when Q = 1, and that E differs from E° when Q ≠ 1. (Guide: “Standard conditions are just one point on the journey”)
- I can describe the cell potential as a drive towards equilibrium that is larger the further the cell is from equilibrium. (Guide: Figure 1; Practice Q5(b))
- I can explain why a “dead” cell is at equilibrium (Q = K, E = 0) rather than empty of reactant. (Guide: Worked example 3; Practice Q1, Q5(d))
- I can explain why Le Châtelier’s principle is not used for a working cell. (Guide: “Why not Le Châtelier’s principle?”; Practice Q6(a))
Skills
- I can write Q for a cell reaction, leaving out solids, and compare it with 1. (Practice Q4)
- I can predict whether a change such as adding an ion, precipitating an ion or diluting makes E larger or smaller than E°. (Guide: Worked example 1; Practice Q2, Q6(b))
- I can read the Nernst equation qualitatively: Q < 1 gives E > E°, Q > 1 gives E < E°. (Guide: “The Nernst equation, read without a calculator”)
- I can use the Nernst equation to check a prediction, with the correct n. (Practice Q4(d), Q5(c), Q6(c))
Reasoning
- I can identify the anode and the direction of electron flow in a concentration cell from the direction needed to reach equilibrium. (Guide: Figure 2; Practice Q3, Q7(a))
- I can explain why a concentration cell gives a voltage although E° = 0, and when it stops. (Guide: Worked example 2; Practice Q7)
- I can justify a claim about cell potential with the chain: concentration → Q → distance from equilibrium → E. (Practice Q4(c), Q6)
All ticked? Move on to Topic 9.11, Electrolysis and Faraday’s Law, or return to the course roadmap.