24.2 Standard electrode potentials E ⦵ , standard cell potentials E ⦵ cell and the NernstSyllabus2028–2030Topic24.2LevelA2
What you’ll learn10 learning objectivesChoose one objective for a focused lesson, or study the complete topic.24.2.1Terms• Define:: (a) standard electrode (reduction) potential; (b) standard cell potentialSyllabus objective24.2.2Standard hydrogen electrode• Describe the standard hydrogen electrodeSyllabus objective24.2.3Measuring standard electrode potentials• Describe methods used to measure the standard electrode potentials of:: (a) metals or non-metals in contact with their ions in aq. solution; (b) ions of the same element in different oxidation statesSyllabus objective24.2.4A standard cell potential by combining two• Calculate a standard cell potential by combining two standard electrode potentialsSyllabus objective24.2.5Standard cell potentials• Use standard cell potentials to:: (a) deduce the polarity of each electrode and hence explain/deduce the direction of electron flow in the external circuit of a simple cell; (b) predict the feasibility of a reactionSyllabus objective24.2.6From E• Deduce from E ⦵ values the relative reactivity of elements, compounds and ions as oxidising agents or as reducing agentsSyllabus objective24.2.7Redox equations using the relevant• Construct redox equations using the relevant half-equationsSyllabus objective24.2.8How the value of an electrode potential, E• Predict qualitatively how the value of an electrode potential, E, varies with the concentrations of the aq. ionsSyllabus objective24.2.9Nernst equation• Use the Nernst equation, E = E° + (0.059/z) log([oxidised]/[reduced]), to predict concentration effects on electrode potential; e.g. Cu2+/Cu and Fe3+/Fe2+.Syllabus objective24.2.10Gibbs free energy and cell potential• Use ΔG° = -nE°cellF.Syllabus objective