Topic 17 - Redox equilibria
 

Unit 6 is a two hour synoptic paper. It contains compulsory questions. As it is a synoptic paper it will cover the topics below and those covered in topics 1-15.

To answer the questions you may refer to your copy of the Nuffield Students’ Book and Data Book. The time allowed to answer the questions means that you do not have time to look up all the information you may wish to refer to in your answers. You should plan to restrict your use of the prescribed texts to relevant passages of background reading or for confirmation of data or equations. Text copied directly from the Students’ Book will not gain you credit.

Redox Equilibria

  1. Recall and be able to use the terms: standard redox potential, standard cell potential and the conventions for representation of cells.
  2. Understand the convention of standard potentials used in Table 6.1 of the Book of Data.
  3. Produce an electrode potential chart from a set of electrode potentials.
  4. Understand the need for a standard electrode.
  5. Apply the anticlockwise rule to show reduction and oxidation.
  6. Be able to calculate a standard cell potential by combining 2 standard redox potentials.
  7. Use the standard cell potential to explain/predict the direction of electron flow from a simple cell and predict the feasibility of a reaction.
  8. Predict the likely direction of a spontaneous change of a redox reaction using suitable electrode potentials and understand why these predictions may not be borne out in practice.
  9. Write ionic half equations and use them to deduce the equations of redox reactions.
  10. Determine oxidation number of an element in an organic species.
  11. Interpret oxidation and reduction in terms of change in oxidation number.
  12. Understand the procedure and principles involved in potassium manganate(VII) and iodine/thiosulphate titrations.
  13. Understand disproportionation reactions in terms of standard electrode potentials.
  14. Be able to establish a simple reactivity (electrochemical) series from experimental observations and relate them to the standard electrode potential.
  15. Understand the application of electrode potential in connection with corrosion problems.
  16. Explain the electrochemical nature of the rusting of iron and the different methods to prevent rusting.
  17. Understand the chemical principle of simple storage cells and the chemistry of the lead-acid battery.
  18. Predict whether a system is at equilibrium, near equilibrium or capable of spontaneous change, using Ecell and Kc as indicators of thermodynamic feasibility.
  19. Demonstrate understanding that some reactions, though predicted as feasible on thermodynamic grounds, do not in practice occur spontaneously.
  20. Evaluate information about batteries and cells by extraction of information from text and the Book of Data.

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