Important Chemistry Reactions Chart
Must-Know Chemistry Reactions for Quick Revision
Chemical reactions describe how matter transforms by breaking and forming bonds. Mastering these 9 reaction types is essential for board exams and competitive tests. This chart covers all major types with definitions and balanced equations for quick revision.
⚗️ All Reaction Types
Type 01
Combination Reactions
Two or more substances combine to form a single product. A + B → AB
⚡ Examples
2Mg + O₂ → 2MgO
CaO + H₂O → Ca(OH)₂
2SO₂ + O₂ → 2SO₃
N₂ + 3H₂ → 2NH₃
Type 02
Decomposition Reactions
A single compound breaks down into two or more simpler products. AB → A + B
⚡ Examples
CaCO₃ → CaO + CO₂
2KClO₃ → 2KCl + 3O₂
2H₂O₂ → 2H₂O + O₂
2AgBr → 2Ag + Br₂
Type 03
Single Displacement
One element displaces another from its compound. A + BC → AC + B
⚡ Examples
Zn + CuSO₄ → ZnSO₄ + Cu
Fe + 2HCl → FeCl₂ + H₂↑
Cl₂ + 2KBr → 2KCl + Br₂
2Al + Fe₂O₃ → Al₂O₃ + 2Fe
Type 04
Double Displacement
Ions of two compounds exchange places to form two new compounds. AB + CD → AD + CB
⚡ Examples
AgNO₃ + NaCl → AgCl↓ + NaNO₃
BaCl₂ + Na₂SO₄ → BaSO₄↓ + 2NaCl
HCl + NaOH → NaCl + H₂O
CuSO₄ + 2NaOH → Cu(OH)₂↓ + Na₂SO₄
Type 05
Neutralization Reactions
An acid reacts with a base to form salt and water. H⁺ and OH⁻ ions combine to neutralize each other.
⚡ Examples
HCl + NaOH → NaCl + H₂O
H₂SO₄ + 2KOH → K₂SO₄ + 2H₂O
CH₃COOH + NaOH → CH₃COONa + H₂O
🧮 Acid + Base → Salt + Water
Type 06
Precipitation Reactions
Two soluble salts react to form an insoluble precipitate (↓) that separates from solution.
⚡ Examples
AgNO₃ + NaCl → AgCl↓ + NaNO₃
BaCl₂ + Na₂SO₄ → BaSO₄↓ + 2NaCl
Pb(NO₃)₂ + 2KI → PbI₂↓ + 2KNO₃
Type 07
Redox Reactions
Oxidation and reduction occur simultaneously. One species loses electrons while another gains them.
⚡ Examples
CuO + H₂ → Cu + H₂O
2Fe₂O₃ + 3C → 4Fe + 3CO₂
Cl₂ + 2KI → 2KCl + I₂
Type 08
Gas Evolution Reactions
A gas is produced and released (↑) during the reaction. Common gases: H₂, O₂, CO₂, NH₃.
⚡ Examples
Zn + 2HCl → ZnCl₂ + H₂↑
CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂↑
NH₄Cl + NaOH → NH₃↑ + NaCl + H₂O
Type 09
Important Organic Reactions
Key reactions of carbon compounds — combustion, dehydration, and acid-base reactions.
🔥 Combustion of Methane
CH₄ + 2O₂ → CO₂ + 2H₂O
💧 Dehydration of Ethanol
C₂H₅OH → C₂H₄ + H₂O
🧴 Acetic Acid + Baking Soda
CH₃COOH + NaHCO₃ → CH₃COONa + H₂O + CO₂
💡 Tips & Reference
✏️ Quick Tips
⭐Always balance the equation first — check atoms on both sides.
⭐Write physical states (s), (l), (g), (aq) if required by your exam board.
⭐Identify the reaction type before attempting to balance it.
⭐Practice writing equations daily — repetition is the key.
⭐↓ means precipitate formed; ↑ means gas evolved.
📋 Types at a Glance
🔗 CombinationA + B → AB
💥 DecompositionAB → A + B
🔄 Single Disp.A+BC → AC+B
🔀 Double Disp.AB+CD → AD+CB
⚖️ NeutralizationAcid+Base → Salt+H₂O
⚡ RedoxOxidation + Reduction
🧠 Remember!
Practice makes perfect. Revision makes it permanent.
Master these 9 reaction types and you'll be prepared for any chemistry exam. Understand the why behind each reaction, not just the formula.
❤️ Master Reactions, Master Chemistry!
❓ Frequently Asked Questions
🔬 What is a chemical reaction?
A chemical reaction is a process where one or more substances (reactants) are converted into different substances (products) by breaking and forming chemical bonds. Signs include colour change, gas evolution, precipitate formation, and temperature change.
🔗 What is a combination reaction?
A combination reaction (synthesis reaction) is where two or more substances combine to form a single new product. General form: A + B → AB. Example: 2Mg + O₂ → 2MgO. These reactions are often exothermic.
💥 What is a decomposition reaction?
A decomposition reaction is where a single compound breaks into two or more simpler substances when energy (heat, light, electricity) is applied. General form: AB → A + B. Example: CaCO₃ → CaO + CO₂. These are generally endothermic.
⚖️ What is a neutralization reaction?
A neutralization reaction occurs when an acid and a base react to form salt and water. H⁺ ions from the acid combine with OH⁻ ions from the base. General equation: Acid + Base → Salt + Water. Example: HCl + NaOH → NaCl + H₂O. Always exothermic.
⚡ What are redox reactions?
Redox reactions involve simultaneous oxidation (loss of electrons) and reduction (gain of electrons). The reducing agent gets oxidized; the oxidizing agent gets reduced. Example: CuO + H₂ → Cu + H₂O — CuO is reduced to Cu; H₂ is oxidized to H₂O.
