WACE Chemistry — Unit 3
Electrochemical Series — Flashcards & Quiz
The electrochemical series ranks half-reactions by their standard reduction potential (E°), and WACE Chemistry Year 12 Unit 3 uses it to predict redox reaction direction, calculate cell EMF, and identify the strongest oxidant and reductant. The series is your lookup table for every galvanic cell calculation.
Key Points
- Half-reactions are listed as reductions; the higher the E°, the greater the tendency to gain electrons (be reduced).
- Strongest oxidant = top of the table (largest positive E°); strongest reductant = bottom of the table (most negative E°).
- Predicting spontaneity: a species is oxidised by anything above it in the table. Spontaneous means E°_cell > 0.
- Cell EMF: E°_cell = E°(cathode) – E°(anode). Positive means the reaction proceeds spontaneously as written.
- Standard conditions: 25°C, 1 mol L⁻¹ solutions, 100 kPa gas pressure. Changes to conditions alter actual cell voltage.
- E° is INTENSIVE — do NOT multiply by stoichiometric coefficients when balancing half-equations.
Common Mistakes to Avoid
- Multiplying E° by stoichiometric coefficients — it's intensive and does not scale.
- Forgetting to reverse the sign of E° when flipping a half-equation from reduction to oxidation.
- Confusing cathode (reduction, larger E°) with anode (oxidation, smaller E°).
- Applying the standard series to non-standard conditions without noting the limitation.
- Calculating E°_cell as anode – cathode — it's the other way around.
Exam Strategy
SCSA Unit 3 electrochemistry questions give you a table of E° values and ask you to predict spontaneity or calculate cell EMF. Method: (1) identify the strongest oxidant and strongest reductant, (2) write the two half-equations with correct directions, (3) apply E°_cell = E°_cathode – E°_anode, (4) interpret the sign (positive = spontaneous).
Sample Flashcards
Q1: How does the electrochemical series predict spontaneous reactions?
Lists half-reactions by E°. Spontaneous if the oxidising agent has MORE POSITIVE E° than the reducing agent. More active metals displace less active ones from solution.
Sample Quiz Questions
Q1: A more active metal can displace a less active metal from solution.
Answer: TRUE
The more active metal oxidises, reducing the less active metal's ions.
Revision Tip
Reading the electrochemical series is a pattern skill — drill a Revizi deck that gives you pairs of half-cells and asks you to predict direction and calculate EMF.
Related Concepts
Last updated: March 2026 · 1 flashcards · 1 quiz questions