1. Which process is oxidation?
- Electron loss
- Electron gain
- Proton gain only
Check the answer and reasoning
Electron loss
Oxidation and reduction occur together through electron transfer.
CHEM / IGCSE
Electrolysis, metals and redox
Oxidation is electron loss and reduction is electron gain. Electrolysis uses electrical energy to drive decomposition; cations migrate to the negative cathode and anions to the positive anode.
Learning objectives
- Explain electrolysis, metals and redox using a concrete example.
- Apply the worked method and justify each step.
- Recognise the limitation described in the final check.
The big idea
Oxidation is electron loss and reduction is electron gain. Electrolysis uses electrical energy to drive decomposition; cations migrate to the negative cathode and anions to the positive anode.
A reactivity series predicts displacement and extraction methods. Molten and aqueous electrolytes can give different products because water provides competing species; electrode material can also matter.
Equations and relationships
Reduction at a cathode.
Worked example
How many electrons reduce one Cu²⁺ ion to copper?
Follow the solution
Two electrons balance the +2 charge, producing a neutral atom.
Investigate and explain
Predict the worked result before calculating. Change one input, record the new result, and explain which assumptions still hold.
Use the evidence activity below; no exact PhET model is claimed.
Check your understanding
2. How many electrons reduce one Cu²⁺ ion to copper?
- 1
- 2
- 4
Check the answer and reasoning
2
Two electrons balance the +2 charge, producing a neutral atom.
3. Will a less reactive metal displace a more reactive metal from its salt?
- Yes
- Always if heated
- No
Check the answer and reasoning
No
Displacement requires the added metal to be more reactive under the relevant conditions.