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Oxidation–Reduction Processes · Part 1 of 2
6 exam-style questions with model answers, plus 8 quick multi-choice questions — every question on this part of the standard, grouped by the 2 pages of notes they come from.
Write a full answer before you reveal the model one. That comparison is where the learning happens.
State the standard conditions for a reduction potential, explain why the standard hydrogen electrode is assigned a value of 0.00 V, and state what a more positive E° indicates.
Explain why the E° value is unchanged when a half equation is multiplied through, using the silver half equation as an example.
Compare and contrast what the reduction potential table tells you with what the reactivity series tells you, and justify why the table is the more powerful tool.
Calculate E°cell for the reaction between zinc metal and silver ions, and state whether it is spontaneous. (E° Ag+/Ag = +0.80 V; E° Zn2+/Zn = −0.76 V)
Explain, with a calculation, why acidified potassium permanganate oxidises chloride ions but acidified potassium dichromate does not, and state the observations in each case. (E° MnO4−/Mn2+ = +1.51 V; E° Cr2O72−/Cr3+ = +1.33 V; E° Cl2/Cl− = +1.36 V)
Aluminium has E° = −1.66 V for Al3+/Al, and water has E° = −0.83 V for the reduction of water to hydrogen. This predicts aluminium should react vigorously with water, yet aluminium saucepans are stable. Justify why the prediction fails, and evaluate what this reveals about the limitations of E° as a predictive tool.