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Major Types of Chemical Reactions

May 16, 2025

Lecture Notes: Five Major Types of Chemical Reactions

Overview

  • The lecture discusses five major types of chemical reactions:
    1. Synthesis Reaction
    2. Decomposition Reaction
    3. Combustion Reaction
    4. Single Replacement Reaction
    5. Double Replacement Reaction
  • Focus on identifying and differentiating between these types of reactions by looking at their chemical equations.

1. Synthesis Reaction

  • Definition: A compound is made from simpler materials.
  • Example: \
    • Carbon + Oxygen gas → Carbon Dioxide (CO₂).
    • Sodium + Chlorine gas (Cl₂) → Sodium Chloride (NaCl).
  • General Form: A + B → AB.
  • Note: Equations might not be balanced; focus on rearrangement of elements.

2. Decomposition Reaction

  • Definition: A compound is broken down into simpler compounds or elements.
  • Example:
    • Water (H₂O) → Hydrogen + Oxygen gas.
    • Calcium Carbonate (CaCO₃) → Calcium Oxide (CaO) + Carbon Dioxide (CO₂).
  • General Form: AB → A + B.

3. Combustion Reaction

  • Definition: Burning where a compound containing carbon and hydrogen reacts with oxygen gas, producing CO₂ and H₂O.
  • Examples:
    • Methane (CH₄) + O₂ → CO₂ + H₂O.
    • Propane (C₃H₈) + O₂ → CO₂ + H₂O.
    • Ethanol (C₂H₅OH) + O₂ → CO₂ + H₂O.
  • General Form: CₓHᵧ(Oₙ) + O₂ → CO₂ + H₂O.

4. Single Replacement Reaction

  • Definition: One element starts by itself and replaces another in a compound.
  • Example:
    • Iron (Fe) + Copper Chloride (CuCl₂) → Copper (Cu) + Iron Chloride (FeCl₂).
    • Copper (Cu) + Silver Nitrate (AgNO₃) → Silver (Ag) + Copper Nitrate (Cu(NO₃)₂).
  • General Form: A + BC → B + AC.
  • Analogy: Like a dance where one person cuts in and replaces another.

5. Double Replacement Reaction

  • Definition: Positive and negative ions in two compounds switch places.
  • Example:
    • Barium Chloride (BaCl₂) + Sodium Sulfate (Na₂SO₄) → Barium Sulfate (BaSO₄) + Sodium Chloride (NaCl).
    • Potassium Bromide (KBr) + Silver Nitrate (AgNO₃) → Potassium Nitrate (KNO₃) + Silver Bromide (AgBr).
  • General Form: AB + CD → AD + BC.
  • Analogy: Like two dancing couples switching partners.

Summary

  • Synthesis: Simple → Complex.
  • Decomposition: Complex → Simple.
  • Combustion: Carbon compound + O₂ → CO₂ + H₂O.
  • Single Replacement: Element replaces one in a compound.
  • Double Replacement: Ions in compounds exchange places.

Next Steps

  • Practice identifying reaction types by analyzing more chemical equations.

Full transcript