P2.The Rate and Extent Of Chemical Change

Cards (30)

  • What can chemical reactions occur at?
    Vastly different rates
  • What is a significant factor in how fast chemical reactions proceed?
    Reactivity of chemicals
  • What can be manipulated to speed up or slow down chemical reactions?
    Temperature
    Concentration and Pressure
    Surface Area
    Presence of Catalyst
  • Who determines the effect of different variables on reaction rate in industry?
    Chemists and chemical engineers
  • What do chemists and chemical engineers optimize in their processes?
    Product yield and reaction time
  • What is the formula for mean rate of reaction using reactants?
    Mean rate = quantity of reactant used / time taken
  • What is the formula for mean rate of reaction using products?
    Mean rate = quantity of product formed / time taken
  • How can the quantity of reactant or product be measured?
    By mass in grams or volume in cm³
  • What are the units of rate of reaction?
    g/s or cm³/s
  • What additional units are required for Higher Tier students?
    mol/s
  • How can students calculate the mean rate of a reaction?
    From quantity of reactant used and time taken
  • What should students be able to draw and interpret regarding reactions?
    Graphs showing quantity of product against time
  • What can students use the slope of a tangent to measure?
    The rate of reaction at a specific time
  • What factors affect the rates of chemical reactions?
    Concentration, pressure, surface area, temperature, catalysts
  • How does increasing concentration affect reaction rates?
    It increases the frequency of collisions
  • What does collision theory explain?
    For particles to react they must collide with sufficient energy.
  • What is the minimum energy required for particles to react called?
    Activation energy
  • How does increasing temperature affect reaction rates?
    It increases collision frequency and energy
  • What do catalysts do in chemical reactions?
    Change the rate without being used up
  • How do catalysts increase reaction rates?
    By providing a pathway with lower activation energy
  • What are reversible reactions?
    Reactions where products can form reactants
  • How can the direction of reversible reactions be changed?
    By changing the conditions
  • What happens if a reversible reaction is exothermic in one direction?
    It is endothermic in the opposite direction
  • What is reached when a reversible reaction occurs in a closed system?
    Equilibrium
  • What does Le Chatelier’s Principle predict?
    The system responds to counteract changes
  • What happens if the concentration of a reactant is increased?
    More products will be formed
  • What happens if the concentration of a product is decreased?
    More reactants will react
  • How does increasing temperature affect products at equilibrium in an endothermic reaction?
    Relative amount of products increases
  • How does decreasing temperature affect products at equilibrium in an exothermic reaction?
    Relative amount of products increases
  • What happens to equilibrium position with increased pressure in gaseous reactions?
    Shifts towards the side with fewer molecules