24. Electrochemistry
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24.1 Electrolysis
24.1.1The identities of substances liberated during
• Predict the identities of substances liberated during electrolysis from the state of electrolyte (molten or aqueous), position in the redox series (electrode potential) and concentration
24.1.2The relationship F = Le between the Faraday
• State/apply: the relationship F = Le between the Faraday constant, F, the Avogadro constant, L, and the charge on the electron, e
24.1.3Calculate
• Calculate:: (a) the quantity of charge passed during electrolysis, using Q = I t; (b) the mass and/or volume of substance liberated during electrolysis
24.1.4Determination of a value of the Avogadro
• Describe the determination of a value of the Avogadro constant by an electrolytic method ⦵ ⦵
24.2 Standard electrode potentials E ⦵ , standard cell potentials E ⦵ cell and the Nernst
24.2.1Terms
• Define:: (a) standard electrode (reduction) potential; (b) standard cell potential
24.2.2Standard hydrogen electrode
• Describe the standard hydrogen electrode
24.2.3Measuring 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 states
24.2.4A standard cell potential by combining two
• Calculate a standard cell potential by combining two standard electrode potentials
24.2.5Standard 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 reaction
24.2.6From E
• Deduce from E ⦵ values the relative reactivity of elements, compounds and ions as oxidising agents or as reducing agents
24.2.7Redox equations using the relevant
• Construct redox equations using the relevant half-equations
24.2.8How the value of an electrode potential, E
• Predict qualitatively how the value of an electrode potential, E, varies with the concentrations of the aq. ions
24.2.9Nernst 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+.
24.2.10Gibbs free energy and cell potential
• Use ΔG° = -nE°cellF.