Types of Reactions
Reactions fall into synthesis, decomposition, single and double replacement and combustion.
About this topic
The main types of chemical reactions are synthesis (A + B → AB), decomposition (AB → A + B), single replacement (A + BC → AC + B), double replacement (AB + CD → AD + CB) and combustion (fuel + O2 → CO2 + H2O). Other important categories are acid-base neutralisation and oxidation-reduction (redox).
Classifying reactions helps you predict products. In synthesis, simple substances join, such as 2Mg + O2 gives 2MgO. In decomposition, one compound splits, often with heat or electricity, such as 2H2O giving 2H2 + O2. Single replacement involves a more reactive element displacing a less reactive one, while in double replacement ions swap partners, usually forming a precipitate, gas or water. Combustion needs oxygen and releases heat and light. Many reactions fit more than one category, for example burning magnesium is both synthesis and combustion, and also redox.
Example: rusting is synthesis, baking soda in a hot oven is decomposition, zinc in copper sulfate is single replacement, and an antacid with stomach acid is double replacement or neutralisation.
Students sometimes memorise the patterns but ignore conditions; a replacement reaction only occurs if the free element is more reactive. Use the types as guidelines rather than rigid rules, and always balance the final equation.
Key ideas
- A + B → AB synthesis
- AB → A + B decomposition
- Combustion needs oxygen
Quick check
Use cases: where Types of Reactions helps
- Homework: review the key idea behind Types of Reactions before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Types of Reactions without notes.
- Visual learning: play with the interactive lab to see how Types of Reactions changes when you adjust its inputs.
- Teaching a friend: explain Types of Reactions in your own words, then compare your version with the key ideas.
Chemistry explains medicine, food, cleaning products, fuels and building materials.
Frequently asked questions
What is Types of Reactions?
Reactions fall into synthesis, decomposition, single and double replacement and combustion.
What will I learn in Types of Reactions?
A + B → AB synthesis. AB → A + B decomposition. Combustion needs oxygen.
Is Types of Reactions part of Chemistry?
Yes. It is one of 150 Chemistry topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Types of Reactions lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Types of Reactions?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.