Equilibria

• what is a reversible reaction

  when the products can react together to form the original reactants
• what does this show: $\leftrightarrow$


  it shows a reaction is reversible as it has a forwards and a backwards reaction
• what is dynamic equilibrium

  for a reversible reaction in a closed system, when the forwards and backwards reaction have an equal rate of reaction. the concentrations of reactants and products remain constant
• what is the equilibrium position

  the description of the relative amounts of reactants and products in a reaction mixture at equilibrium
• if the equilibrium position lies to the right, the concentration of products is higher than the reactants and vice versa
• what is Le Chateliers' Principle

  if a change is made to the conditions of a reaction at dynamic equilibrium, the equilibrium position will shift in order to minimise change
• what happens to the equilibrium position if you increase the concentration

  increasing the concentration of a reactant shifts the equilibrium position to the right and the concentration of products (yield) increases
• what happens to the equilibrium position if you increase the temperature

  increasing the temperature shifts the equilibrium position in the endothermic direction to take in energy and minimise temperature increase
• what happens to the equilibrium position if you increase the pressure

  increasing the pressure shifts the equilibrium position to the side with the least moles of gas
• what happens to the equilibrium position if you add a catalyst

  it will not affect it as they speed up the rate of reaction in both directions equally
• what 2 factors affect the equilibrium yield

  pressure & temperature
• why do you need to compromise on a pressure for the manufacture of products

  as a high pressure increases the yield of the product however too high a pressure is expensive and dangerous
• why do you need to compromise on a temperature for the manufacture of products

  as a low temperature increases the yield of the products however too low a temperature decreases the rate of reaction to a point where its not profitable