Work through the list without notes. If you cannot do a statement, follow its link, then come back. Guide = study guide; Practice = practice questions.
Understanding
- I can explain what a half-reaction shows and why the electrons are products in an oxidation and reactants in a reduction. (Guide: “Half-reactions: showing where the electrons go”; Practice Q2, Q4)
- I can explain why electrons lost must equal electrons gained, and why free electrons never appear in an overall equation. (Guide: “The one rule that matters most”)
- I can explain why H₂O and H⁺ (or OH⁻ in basic solution) may be added when balancing, but no other species. (Guide: “Why water and H⁺?”)
Skills
- I can split a redox equation into its oxidation and reduction half-reactions, using oxidation numbers to decide which is which. (Practice Q2, Q6)
- I can balance a half-reaction in acidic solution in the right order: other atoms, O with H₂O, H with H⁺, charge with e⁻. (Guide: permanganate example; Practice Q1, Q4)
- I can check the number of electrons in a half-reaction against the change in oxidation number. (Guide: Worked example 2; Practice Q1)
- I can multiply half-reactions to their lowest common multiple of electrons, add them and cancel electrons, H⁺ and H₂O. (Guide: Worked examples 1 and 2; Practice Q3, Q5)
- I can use the coefficients of a balanced redox equation as a mole ratio in a titration calculation. (Guide: “Using the balanced equation as a mole ratio”; Practice Q5)
- Extension: I can balance a redox equation in basic solution. (Guide: “Extension: reactions in basic solution”; Practice Q7)
Reasoning
- I can show that an equation is balanced by checking both atoms and total charge, and explain why atom balance alone is not enough. (Guide: Worked example 1; Practice Q3, Q6)
- I can evaluate a claim that a redox equation is balanced, giving a reason based on charge or on electrons transferred. (Practice Q6)
All ticked? You have finished Unit 4. Move on to Topic 5.1, Reaction Rates, or return to the course roadmap.