SCI10 Q4 MOD4

Lesson 1: Factors Affecting Reaction Rates

  • Collision Theory: Atoms/molecules must collide with sufficient energy to react.

    • Use of analogy: children playing "Pukpok Palayok" to explain collision theory.

    • Activation Energy: Minimum energy required for a reaction to occur, proposed by Svante Arrhenius in 1888.

    • Visualization of reactants' energy dynamics through illustrated figures.

Understanding Rates of Reaction

Factors Altering Reaction Rates

  1. Particle Size / Surface Area: Smaller pieces increase reaction rate due to greater surface area.

  2. Concentration of Reactants: Higher concentration leads to more frequent collisions (e.g., in corrosion).

  3. Temperature: Higher temperatures increase particle movement and reaction rates.

  • Example: Chilling food slows spoilage; drying lowers moisture to extend shelf life.

  1. Presence of Catalysts: Substances that speed up reactions or inhibit reactions, affecting activation energy.

Detailed Examination of Reaction Factors

1. Particle Size / Surface Area

  • Smaller reactants lead to quicker reactions (e.g., firewood).

  • Larger pieces burn slowly; smaller pieces increase chance of collisions.

2. Concentration

  • Defines number of solute particles in a solution.

  • Higher concentration increases collision frequency (corrosion example).

    • Illustration of particles in varying concentrations.

3. Temperature

  • Increased temperature boosts molecular movement.

  • Visual representation showing molecular activity in hot vs. cold water.

  • Importance in food preservation practices: chilling and drying to prolong shelf life.

4. Catalyst

  • The role of catalysts in speeding reactions (e.g., manganese (IV) oxide with hydrogen peroxide).

  • Catalysts lower activation energy and facilitate faster reactions.