13.3Unit 8: Energy changes and reactions of metals
Metals and their reactions with oxygen — Cambridge Checkpoint Science 0893 Revision Notes & Topical Questions
5 min read 6 parts Lesson 3 of 5 1 quiz
13.3 Metals and their reactions with oxygen — CHECKPOINT (CHEMISTRY) notes: Describe the reactions of metals with oxygen and explain rusting.Reaction — metal + oxygen → metal oxide, an oxidation reactionReactivity — more reactive metals react more quickly: magnesium is more react…
- Heating in air
- Sodium, potassium and calcium
- Oxide layer
- Conditions
- Same nails
- Galvanising
Section 1 of 6Metals and oxygen
- Reaction
- metal + oxygen → metal oxide, an oxidation reaction
- Reactivity
- more reactive metals react more quickly: magnesium is more reactive than iron
- Heating in air
- many metals react with oxygen if they get hot enough
Section 2 of 6Very reactive metals
- Sodium, potassium and calcium
- react with oxygen without heating; a freshly cut shiny surface soon becomes dull
- Oxide layer
- forms on the surface and stops further reaction
- Storage
- kept under oil to prevent reaction with air and water vapour
Section 3 of 6Unreactive metals
- Gold
- does not react with oxygen and is inert
- Silver
- reacts slowly; silver goes black over time as silver oxide forms
Section 4 of 6Rusting
- Rust
- iron + oxygen → iron oxide, an orange-brown solid
- Conditions
- needs both water and oxygen; water is needed but is not in the equation
- Effect
- the iron changes and loses its properties, e.g. a girder can fall apart
- Speed
- slow, because iron is not very reactive with oxygen
Section 5 of 6Rusting experiment
| Tube | Conditions | Result |
|---|---|---|
| 1 | Moist air | Nail rusted |
| 2 | Water and air | Very rusty |
| 3 | Dry air (calcium chloride) | No rust |
| 4 | Boiled water under oil, no air | Small amount of rust |
- Same nails
- the same type of nail in each tube makes it a fair test
Section 6 of 6Protecting iron
- Painting
- stops oxygen reaching the iron
- Galvanising
- covering iron with a layer of zinc prevents oxygen reaching it
Marked practiceQuizzes for this lesson
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Step-by-step problem-solving guide, mark scheme criteria, and experimental error analysis curated by Dr. Khaled Dabour (DABOURHUB).
1. Identify all given values and convert non-standard units, 2. State the primary formula or physiological/chemical principle, 3. Calculate to 3 significant figures and clearly state units.
Avoid confusing independent vs dependent variables in practical questions. In calculation questions, double-check percentage change formula: (change / original) × 100.