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Equilibrium (K Constant (The equilibrium constant (K) for the reaction is…
Equilibrium
K Constant
The equilibrium constant (K) for the reaction is defined as the ratio (at equilibrium) of the concentrations of the products raised to their stoichiometric coefficients divided by the concentrations of the reactants raised to their stoichiometric coefficients:
For the reaction aA+bB⇌cC+dD,
K = [A]^a [B]^b / [C]^c [D]^d
A large equilibrium constant indicates that the equilibrium point for the reaction lies to the right, which means that ther are high concentrations of products and low concentrations of reactants
When the equilibrium constant is very small, it indicates that the equilibrium point for the reaction lies far to the left, and there are high concentrations of reactants and low concentrations of products
When K < 1, the reverse reaction is favored. When K = 1, neither direction is favored. When K > 1, the forward reaction is favored
ICE Tables
ICE table: I = initial , C = change, E = equilibrium
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2.) Calculate the change in concentration that occurs for the reactant or product whose concentration is known both initially and at equilibrium
3.) Use the calculated change and stoichiometric relationships from the balanced chemical to find the changes in concentration of all other reactants and products
1.) Set up an ICE table using a balanced equation as a guide. Fill in the known initial concentrations and equilibrium concentrations of the reactants and products
Le Chatelier's Principal
If a stress is applied to a system in a dynamic equilibrium, the system changes in a way that relieves that stress.
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Change in Concentration
Decreasing the concentration of one or more of the reactants causes the reaction to shift in the direction of the reactants (shift to the left).
Decreasing the concentration of one or more of the products causes the reaction to shift in the direction of the products (shift to the right).
Increasing the concentration of one or more of the reactants causes the reaction to shift in the direction of the products ( shift to the right).
Increasing the concentration of one or more of the products causes the reaction to shift in the direction of the reactants (shift to the left).
Change in Temperature
Exothermic Reaction
Increasing the temperature causes an exothermic reaction to shift left (in the direction of the reactants). The value of the equilibrium constant decreases.
Decreasing the temperature causes an exothermic reaction to shift right (in the direction of the products). The value of the equilibrium constant increases.
Endothermic Reaction
Increasing the temperature causes an endothermic reaction to shift right (in the direction of the products). The equilibrium constant increases.
Decreasing the temperature causes an endothermic reaction to shift left (in the direction of the reactants). The equilibrium constant decreases.