Overview of Chemical Reaction Types

Aug 22, 2024

Lecture Notes: Types of Chemical Reactions

1. Combustion Reaction

  • Definition: A reaction where a substance burns, releasing heat energy.
  • Example: Octane (found in gasoline) reacts with oxygen to produce CO2 and H2O. Water is typically in vapor form due to high temperatures.
  • Features:
    • Hydrocarbon reacts with oxygen.
    • Produces carbon dioxide and water.
    • Generates a lot of heat.

2. Synthesis Reaction (Combination Reaction)

  • Definition: Two or more reactants combine to form a more complex product.
  • Examples:
    • Magnesium reacts with oxygen to form Magnesium Oxide.
    • Magnesium Oxide reacts with CO2 to form Magnesium Carbonate.
  • Features:
    • Elements or compounds combine to form a larger compound.

3. Decomposition Reaction

  • Definition: A complex substance breaks down into simpler substances.
  • Examples:
    • Magnesium Carbonate decomposes upon heating to Magnesium Oxide and CO2.
    • Mercury Oxide decomposes into Mercury and Oxygen upon heating.
    • Water decomposing into Hydrogen and Oxygen gases with electricity.
  • General Equation: AB → A + B.

4. Single Replacement Reaction (Single Displacement)

  • Definition: An element replaces another in a compound.
  • Examples:
    • Zinc reacts with Copper Chloride to form Zinc Chloride and Copper.
    • Bromine reacts with Sodium Iodide to form Sodium Bromide and Iodine.
    • Iron reacts with HCl to form FeCl2 and H2.
  • General Equation: A + BC → AC + B.
  • Note: Generally metals replace metals, nonmetals replace nonmetals.

5. Double Replacement Reaction (Double Displacement)

  • Definition: Exchange of ions between two compounds.
  • Types:
    • Precipitation Reaction: Forms an insoluble product.
      • Example: Silver Nitrate + Sodium Chloride → Silver Chloride (solid) + Sodium Nitrate.
    • Acid-Base Neutralization: Forms water and a salt.
      • Example: HCl + NaOH → NaCl + H2O.
    • Gas Evolution Reaction: Produces a gas.
  • General Equation: AB + CD → AD + CB.

6. Combustion Reaction Review

  • Hydrocarbon + O2 → CO2 + H2O.
  • Redox reactions since there is a transfer of electrons.

Redox Reactions

  • Combustion and Single Replacement are always redox.
  • Decomposition & Synthesis:
    • If pure elements form compounds or vice versa, it's a redox reaction.

Examples and Classification Quizzes

  • Decomposition: Calcium Hydroxide decomposes to Calcium Oxide and Water.
  • Single Replacement: Zinc reacts with Nickel Chloride to form Zinc Chloride and Nickel.
  • Synthesis: Barium Oxide + CO2 → Barium Carbonate.
  • Gas Evolution: Sodium Bicarbonate + HCl → NaCl + H2O + CO2.

Summary

  • Decomposition: AB → A + B.
  • Synthesis: A + B → AB.
  • Single Replacement: A + BC → AC + B.
  • Double Replacement: AB + CD → AD + CB.
  • Combustion: Hydrocarbon + O2 → CO2 + H2O.
  • Types of Double Replacement:
    • Precipitation
    • Acid-Base Neutralization
    • Gas Evolution