Half-Equations Past Papers
Writing Ionic Half-Equations · IGCSE Chemistry 0620 · Extended Level
CATHODE (−): Cations gain electrons → REDUCTION
ANODE (+): Anions lose electrons → OXIDATION
OIL RIG: Oxidation Is Loss · Reduction Is Gain
At which electrode does reduction occur during electrolysis?
What does the acronym OILRIG stand for?
Is the process at the anode oxidation or reduction? Explain why.
During the electrolysis of copper(II) sulfate solution using inert electrodes, copper is deposited. State which electrode this occurs at and identify the type of reaction taking place.
Define the term oxidation in terms of electron transfer. Give one example of a species being oxidised at the anode during electrolysis.
Write the ionic half-equation for the formation of lead at the cathode during the electrolysis of molten lead(II) bromide.
Write the ionic half-equation for the production of hydrogen gas at the cathode during the electrolysis of dilute sulfuric acid.
Write the ionic half-equation for the deposition of copper at the cathode during the electrolysis of copper(II) sulfate solution.
Write the ionic half-equation for the formation of aluminium at the cathode during the electrolysis of molten aluminium oxide.
During electrolysis of brine (concentrated sodium chloride solution), hydrogen gas is produced at the cathode. Write the ionic half-equation for this reaction.
Write the ionic half-equation for the production of chlorine gas at the anode during the electrolysis of concentrated hydrochloric acid.
Write the ionic half-equation for the production of oxygen gas at the anode during the electrolysis of dilute sulfuric acid.
Write the ionic half-equation for the oxidation of bromide ions at the anode to form bromine.
During electrolysis of molten lead(II) bromide, bromine is produced at the anode. Write the ionic half-equation for this reaction and state the type of reaction occurring.
[Extended] During the industrial electrolysis of brine, three useful products are made. (a) Name the product at the anode. (b) Write the ionic half-equation for its formation. (c) Name one industrial use of this product.
Quick Reference Card
CATHODE (Reduction)
Pb²⁺ + 2e⁻ → Pb
Cu²⁺ + 2e⁻ → Cu
Al³⁺ + 3e⁻ → Al
2H⁺ + 2e⁻ → H₂
ANODE (Oxidation)
2Cl⁻ → Cl₂ + 2e⁻
2Br⁻ → Br₂ + 2e⁻
4OH⁻ → 2H₂O + O₂ + 4e⁻
2O²⁻ → O₂ + 4e⁻
⚡ OIL RIG: Oxidation Is Loss · Reduction Is Gain ⚡
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