Rusting and Redox

IGCSE Edexcel Chemistry
2.18-2.20 Rusting and redox terms
Key Concept: Rusting needs water and oxygen. Oxidation and reduction can be described by oxygen transfer or electron transfer.

Section A: Rusting

1. State the two conditions needed for iron to rust. [2]
2. Describe an experiment using three test tubes to show that both air and water are required for rusting. [3]
3. State three methods to prevent rusting. [3]

Section B: Redox

4. Define oxidation and reduction in terms of oxygen and electrons. [4]
5. In the reaction Fe2O3 + 3CO -> 2Fe + 3CO2, identify the oxidizing agent and the reducing agent. [2]

Total marks: 14

Mark Scheme

1. Water and oxygen [2]
2. Example: dry air with calcium chloride (no rust); boiled water with oil layer (no rust); water + air (rust). Any correct setup with controls [3]
3. Painting, oil/grease, galvanizing, sacrificial protection, plastic coating [3]
4. Oxidation: gain of oxygen or loss of electrons; reduction: loss of oxygen or gain of electrons [4]
5. Oxidizing agent: Fe2O3; reducing agent: CO [2]