Types of Chemical Reactions — Interactive Diagram
See the four main types of chemical reactions with a simple example of each.
TL;DR: See the four main types of chemical reactions with a simple example of each.
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Types of Chemical Reactions: See the four main types of chemical reactions with a simple example of each.
Why it matters: Combination, decomposition, displacement and double-displacement reactions are the backbone of the Chemical Reactions chapter.
Types of Chemical Reactions — Step by Step
- COMBINATION: two or more substances join to form one product. Example: 2Mg + O₂ → 2MgO.
- DECOMPOSITION: one substance breaks into two or more. Example: CaCO₃ → CaO + CO₂ (on heating).
- DISPLACEMENT: a more reactive element pushes out a less reactive one (Fe + CuSO₄ → FeSO₄ + Cu). DOUBLE DISPLACEMENT: two compounds swap partners (AgNO₃ + NaCl → AgCl↓ + NaNO₃).
Quick Notes — the Exam Crux
- Combination: two or more reactants form one product. e.g. CaO + H₂O → Ca(OH)₂.
- Decomposition: one reactant breaks into two or more (needs heat/light/electricity). e.g. 2FeSO₄ --heat--> Fe₂O₃ + SO₂ + SO₃.
- Displacement: a more reactive element displaces a less reactive one. e.g. Fe + CuSO₄ → FeSO₄ + Cu.
- Double displacement: two compounds exchange ions, often forming a precipitate. e.g. Na₂SO₄ + BaCl₂ → BaSO₄↓ + 2NaCl.
- Oxidation = gain of oxygen / loss of hydrogen; Reduction = loss of oxygen / gain of hydrogen — they always occur together (redox).
- A balanced equation must have equal atoms of each element on both sides.
Remember It (Memory Trick)
Combination = "join", Decomposition = "break", Displacement = "kick out", Double displacement = "swap partners", Redox = oxidation and reduction happening together.
Real-Life Example
An iron gate rusting through the monsoon (iron + oxygen + water → rust) is oxidation; milk turning to curd and a firecracker bursting are chemical reactions too — each makes new substances with new properties.
Test Yourself
Classify the reaction: Fe + CuSO₄ → FeSO₄ + Cu.
A displacement reaction — the more reactive iron displaces copper.
What is a decomposition reaction, and what usually drives it?
A single reactant breaks into two or more products; it usually needs energy as heat, light or electricity.
In a redox reaction, what happens to the substance that is oxidised?
It gains oxygen (or loses hydrogen) — in electron terms, it loses electrons.
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