Question 1

What is NCEA AS 91393 about?

Accepted Answer

You need to show you understand how oxidation and reduction reactions work, including how to use electrode potentials to predict whether reactions will happen spontaneously. This standard covers reactions in electrochemical cells (like batteries) and electrolytic cells (where you use electricity to force a reaction), and you may need to do calculations with electrode potentials.

Question 2

What do students need to do for AS 91393?

Accepted Answer

1. Describe oxidation-reduction processes using correct chemistry vocabulary, symbols and conventions 2. Use reduction potentials to explain the relative strengths of oxidants and reductants in reactions 3. Predict whether redox reactions will occur spontaneously and explain why (or why not) 4. Apply electrode potential calculations to electrochemical and electrolytic cell reactions 5. Make links between electrode potentials, equations, observations and calculations to explain how redox processes work

Question 3

What's the difference between Achieved, Merit, and Excellence for AS 91393?

Accepted Answer

Achieved: You describe what happens in redox reactions and correctly use chemistry symbols and vocabulary, possibly including some calculations with electrode potentials. Merit: You explain the links between electrode potentials, the equations, what you observe happening, and your calculations—showing why reactions are spontaneous or non-spontaneous. Excellence: You compare and contrast different redox processes, justify the links between all components (potentials, equations, observations, calculations), and consistently use correct chemistry language throughout to show deep understanding of how spontaneity works.

Question 4

What mistakes do students typically make in AS 91393?

Accepted Answer

1. Confusing oxidation with reduction or getting the direction of electron flow wrong in cell diagrams 2. Not balancing redox half-equations correctly, especially the electrons or H+ / OH- in different conditions 3. Treating standard reduction potentials as if they tell you reaction rate rather than just whether the reaction is spontaneous

Oxidation-reduction

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AS91393 — Oxidation-reduction processes

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