Dynamic equilibrium - Higher tier

When a reversible reaction happens in a closed container, it can achieve a dynamic equilibrium.

At equilibrium:

  • the forward and backward reactions are still happening
  • the rates of the forward and backward reactions are the same
  • the concentrations of the reactants and products remain constant (they do not change)
  • equilibrium can only be achieved if none of the reactants or products can escape. For example if calcium carbonate is heated in a sealed container, breakdown occurs and the following equilibrium is made: CaCO3(s) ⇌ CaO(s) + CO2(g)
  • if this reaction is carried out in an open test tube the breakdown goes to completion: CaCO3(s) → CaO(s) + CO2(g)
  • this occurs as the carbon dioxide gas escapes and the backwards reaction cannot occur.

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