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Half-equations and ionic equationsEdexcel A-Level Chemistry: Flashcards

What these 13 flashcards ask

  • On which side are electrons in an oxidation half-equation?
  • On which side are electrons in a reduction half-equation?
  • Write the half-equation for oxidation of zinc.
  • Write the half-equation for reduction of Cu²⁺.
  • What is the order for balancing a half-equation in acid?
  • Write the half-equation for MnO₄⁻ reduced to Mn²⁺ in acid.
  • Write the half-equation for Cr₂O₇²⁻ reduced to Cr³⁺ in acid.
  • How do you combine two half-equations?
  • Write the overall equation for MnO₄⁻ with Fe²⁺ in acid.
  • Write the overall ionic equation for Fe³⁺ with I⁻.
  • What is a spectator ion?
  • Write the half-equation for chlorine reduced to chloride.
  • How can you check a half-equation is balanced?

Exam questions on Half-equations and ionic equations

  1. A student places a piece of zinc in blue copper(II) sulfate solution. After some time the blue colour fades and a brown-red solid forms on the zinc.
    Write the ionic equation for the reaction, including state symbols.2 marks
  2. Acidified potassium manganate(VII) solution is used to titrate solutions containing iron(II) ions. The purple MnO₄⁻ ion is reduced to the almost colourless Mn²⁺ ion, and Fe²⁺ is oxidised to Fe³⁺.
    Write the overall ionic equation for the reaction between acidified MnO₄⁻ ions and Fe²⁺ ions.2 marks
  3. A student studies two redox reactions of iron ions in aqueous solution. In the first, iron(III) ions oxidise iodide ions. In the second, acidified dichromate(VI) ions oxidise iron(II) ions.
    Write the half-equation for the reduction of Fe³⁺, the half-equation for the oxidation of I⁻ to I₂, and the overall ionic equation.3 marks
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Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).