Reversible reactions and rate of reaction

• Catalyst


  An agent that can increase the rate of a reaction
• Surface Area


  The area of the reactants available for reaction to occur
• Increasing Temperature


  Increases the kinetic energy of molecules, making them collide more frequently and react more quickly
• Catalyst


  A substance that increases the reaction rate without being consumed or permanently altered by the reaction
• Enzyme


  A biological molecule that catalyzes specific chemical reactions
• Substrate-Enzyme Complex


  A complex between the enzyme and substrate that allows the reaction to occur
• Collision Theory Requirements


  Reactants must collide with each other, collide with sufficient energy, and have the correct orientation
• Frequency of Collisions


  Increasing reactant concentration and temperature increases the frequency of collisions
• Surface Area


  Increasing surface area increases the frequency of collisions; decreasing particle size increases surface area
• Catalyst Effect


  Catalysts lower the energy of activation, increase frequency of collisions, and change the orientation of reactants
• Mean Rate of Reaction

  A measure of the change in concentration of reactants or products over time
• Calculating Rate of Reaction


  Plot the graph, find the tangent, find the gradient, and calculate the rate of reaction (r = Δ[C] / Δt)
• Reversible Reactions


  Reactions that can proceed in both the forward and reverse directions
• Equilibrium


  A state where the rates of the forward and reverse reactions are equal, resulting in no net change in concentrations
• Ammonia Synthesis


  A reversible reaction between nitrogen and hydrogen producing ammonia
• Le Chatelier's Principle


  Equilibrium shifts to counteract changes in concentration, temperature, or pressure
• Equilibrium Shift


  Equilibrium shifts in a direction that counteracts the change, restoring the equilibrium
• Ammonia Formation


  Nitrogen and hydrogen react to form ammonia (NH3)
• Haber Process Steps


  1. Mix nitrogen and hydrogen, 2. Add catalyst, 3. React at high temperature and pressure
• Reversible reactions


  Products of the reaction can produce the reactants
• Reversible reactions


  1. Forward reaction

  2. Backward reaction
• One reaction has to be endothermic, the other has to be exothermic
• Equilibrium


  The forward and backward reactions happen at the same rate, the concentrations/mass are constant and stay the same. Can only happen in a closed system.
• Le Chatelier's Principle


  The equilibrium position can be changed by changing the pressure, concentration or temperature of the reaction. The reaction will counteract the change.
• If the equilibrium moved to the left


  There will be more reactants formed
• If the equilibrium moves to the right

  More products will be formed
• Haber Process


  Nitrogen gas + Hydrogen gas -> Ammonia gas
• Haber Process


  • Temp = 450°C
  • Pressure: 200atm
  • Catalyst = Iron
• Increasing temp


  Favours endothermic, to the left, less NH3
• Increasing pressure


  Favours side with less moles, to the right, more NH3