Overview
This lecture introduces the main types of chemical reactions, outlines their defining features, and provides basic examples and key terminology.
Synthesis (Combination) Reactions
- Two or more substances combine to form a single new compound.
- General formula: A + B → AB.
- Example: 2H₂ + O₂ → 2H₂O.
Decomposition Reactions
- A single compound breaks down into two or more simpler substances.
- General formula: AB → A + B.
- Example: 2H₂O → 2H₂ + O₂.
Single Displacement (Replacement) Reactions
- One element replaces another in a compound.
- General formula: A + BC → AC + B.
- Example: Zn + 2HCl → ZnCl₂ + H₂.
Double Displacement (Replacement) Reactions
- Ions in two compounds exchange places to form two new compounds.
- General formula: AB + CD → AD + CB.
- Example: AgNO₃ + NaCl → AgCl + NaNO₃.
Combustion Reactions
- A substance reacts rapidly with oxygen, often producing heat and light.
- General formula: Fuel + O₂ → CO₂ + H₂O (for hydrocarbons).
- Example: CH₄ + 2O₂ → CO₂ + 2H₂O.
Key Terms & Definitions
- Chemical Reaction — A process in which substances change into new substances with different properties.
- Reactant — A starting substance in a chemical reaction.
- Product — A new substance formed in a chemical reaction.
- Synthesis Reaction — Reaction where multiple reactants form a single product.
- Decomposition Reaction — Reaction where a single compound forms multiple products.
- Single Displacement Reaction — Reaction where one element replaces another in a compound.
- Double Displacement Reaction — Reaction where ions swap between compounds.
- Combustion Reaction — Rapid reaction with oxygen releasing energy.
Action Items / Next Steps
- Practice identifying reaction types by classifying given chemical equations.
- Review homework problems on distinguishing and balancing different reaction types.