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Chemical equilibria, Le Chatelier's principle and Kc key terms
Use these key terms for Chemical equilibria, Le Chatelier's principle and Kc in AQA Chemistry 7405. The page is built from approved learning objectives for this topic and links back to the wider unit, topic hub, and related revision assets.
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key terms
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Chemical equilibria, Le Chatelier's principle and Kc
Key terms
dynamic equilibrium
A state in a closed system where the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products.
closed system
A physical system that does not exchange matter with its surroundings, allowing for the establishment of dynamic equilibrium.
Le Chatelier's principle
A principle stating that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change.
concentration change
A change in the amount of reactants or products in a reaction mixture, which can shift the position of equilibrium according to Le Chatelier's principle.
pressure change
An alteration in the force exerted by gas particles in a closed system. In Equilibrium and Le Chatelier's principle, pressure change is used to explain use Le Chatelier's principle to predict the effect of pressure changes with A-Level Chemistry precision.
dynamic equilibrium
A state in a closed system where the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products.
Le Chatelier's principle
A principle stating that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change.
dynamic equilibrium
A state in a closed system where the rate of the forward reaction equals the rate of the reverse reaction, resulting in constant concentrations of reactants and products.
catalyst
A substance that increases the rate of a chemical reaction without being consumed, by providing an alternative reaction pathway with a lower activation energy.
dynamic equilibrium
A state in a closed system where the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products.
Kc expression
An equation that relates the concentrations of reactants and products at equilibrium for a reversible reaction.
homogeneous equilibrium
An equilibrium system where all reactants and products are in the same physical state.
equilibrium constant (Kc)
A numerical value that expresses the ratio of the concentrations of products to reactants at equilibrium for a reversible reaction.
equilibrium concentrations
The concentrations of reactants and products in a system at equilibrium, which remain constant over time.
equilibrium concentration
The concentration of reactants and products in a system at equilibrium, where the rate of the forward reaction equals the rate of the reverse reaction.
Kc expression
A mathematical representation of the equilibrium constant, Kc, expressed as the ratio of the concentrations of products to reactants, each raised to the power of their coefficients in the balanced equation.
equilibrium constant (Kc)
A numerical value that expresses the ratio of the concentrations of products to reactants at equilibrium for a reversible reaction.
units of Kc
The units of Kc depend on the balanced chemical equation; for a reaction aA + bB ⇌ cC + dD, Kc is expressed in terms of mol/dm³ raised to the power of (c+d)-(a+b).
magnitude of Kc
The numerical value of the equilibrium constant Kc, which indicates the ratio of concentrations of products to reactants at equilibrium.
equilibrium position
The state of a reversible reaction where the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products.
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