Edpuzzle notes for Collision theory and factors

• Kinetics

  Study of the rate/speed at which reactions occur
• Reaction

  The breaking and reforming of bonds to make entirely new compounds as products
• Effective collisions


  Reactant particles must collide with proper amount of energy and proper orientation (angle)
• For reaction to occur, reactant particles must collide with proper amount of energy
• For reaction to occur, reactant particles must collide with proper orientation (angle)
• Increasing the number of effective collisions & more effective collisions results in faster reaction.
• Factors affecting rate of reaction

  • Temperature
  • Concentration
  • Surface area
  • Pressure
  • Catalyst
• Type of Reactant

  • Ionic substances in aqueous solution react faster
  • Covalent substances react slower
• Examples of reactions

  • Ag N03 (aq) → Ag + N03
  • H2 (g) I2 (g) → 2HI (g)
• Concentration

  • Increase concentration increases reaction speed
  • More particles increase chance of effective collisions
• Temperature


  • Increase in temperature increases reaction rate
  • Increases number of effective collisions
  • Reactants have more energy when colliding
• Pressure

  • Increase in pressure increases reaction rate (effects gases only)
  • Particles are closer together leading to more collisions
• Surface Area

  • Increase in surface area increases reaction rate
  • More exposed particles can react leading to more effective collisions
• Catalyst


  • Substance that increases reaction rate without being consumed in the reaction
  • Provides an alternate reaction pathway that requires less energy and can be reused
• Potential Energy Diagrams show how energy/heat flows in a reaction from adding reactants to forming products


  Mar 6, 2024
• Activation energy


  Energy required to form the activated complex from reactants
• Enthalpy of a reaction (ΔH)


  Difference between the total enthalpy of the products and the total enthalpy of the reactants
• Reverse Reaction


  Reaction that goes from right to left
• Equilibrium

  • Both forward and reverse reactions are taking place
  • Equations written with a double arrow
  • Equilibrium is dynamic and in constant motion
• Phase Equilibrium


  • Rate of forward phase change equals rate of reverse phase change
  • Rate of condensing equals rate of vaporizing
• Solution Equilibrium

  • Unsaturated: Not at equilibrium (Dissolves more than it precipitates)
  • Saturated: At equilibrium (Dissolves and precipitates equally)
  • Super-saturated: Not at equilibrium (Dissolves less than it precipitates)
• Chemical Equilibrium


  Equilibrium is acquired when rates of forward and reverse reactions are equal, leading to constant concentration
• Le Chatelier's Principle

  A change (stress) is imposed on a system at equilibrium. The position of the equilibrium will shift in a direction that tends to reduce that stress change to re-establish equilibrium.
• Types of stress

  • Concentration
  • Temperature
  • Pressure (gases only)
• Change in concentration

  • If a substance is added (increase concentration), the reaction shifts away from the side of the reaction that you added to
  • If a substance is taken away (decrease concentration), the reaction shifts towards the side of the reaction that you took away from
• Change in temperature

  • Endothermic reactions: Reactants + Heat -> Products
  • Exothermic reactions: Reactants -> Heat + Products
• Change in pressure (gases only)

  • An increase in pressure causes a shift away from the side of the reaction with more moles of gas
  • An decrease in pressure causes a shift towards the side of the reaction with more moles of gas
• Catalyst increases the rate of both the forward and reverse reactions
• Equilibrium is achieved faster but there's no shift