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