(HT only) Count gaseous molecules on each side of an equilibrium equation.

Key terms

• reversible reaction: A chemical reaction that can proceed in both forward and reverse directions. In AQA GCSE Chemistry 8462, use this term specifically when explaining rate of reaction, collision theory, reversible reactions, equilibrium, catalysts, graph gradients, or Le Chatelier's principle.
• dynamic equilibrium: A state in which the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products. In AQA GCSE Chemistry 8462, use this term specifically when explaining rate of reaction, collision theory, reversible reactions, equilibrium, catalysts, graph gradients, or Le Chatelier's principle.
• Le Chatelier's Principle: A principle stating that if a system at equilibrium is subjected to a change in concentration, temperature, or pressure, the system will adjust to counteract that change. In AQA GCSE Chemistry 8462, use this term specifically when explaining rate of reaction, collision theory, reversible reactions, equilibrium, catalysts, graph gradients, or Le Chatelier's principle.
• gaseous molecules: Molecules that exist in the gas phase, which can influence the position of equilibrium in a reaction. In AQA GCSE Chemistry 8462, use this term specifically when explaining rate of reaction, collision theory, reversible reactions, equilibrium, catalysts, graph gradients, or Le Chatelier's principle.

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