Equilibrium: Keq & Le Chatelier's Principle

reversible reaction

the conversion of reactants to products and the conversion of products to reactants occur simultaneously

conditions for equilibrium

1. systems must be closed
2. equilibrium is a dynamic process
3. rates of forward and reverse reactions are equal
4. the amounts of reacts and products don’t have to be equal, but, after equilibrium is attained the amounts of reactants and products will be equal

equilibrium constant

the ratio of the mathematical product of the concentrations of the products of a reactions to the mathematical product of the concentrations of the reactants of the reaction

how do you know a reaction is at equilibrium

1. the rate of the forward reaction is equal to the rate of the reverse reaction
2. concentration of the products and reactants are constant (concentration doesn’t change)

homogenous equilibrium

ALL substances in the reaction exist in the same state

heterogenous equilibrium

substances exist in different states

equilibrium constant expression

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M or mol/L

when writing Keq expressions

ONLY (g) and (aq) reactants/ products are included

EXCLUDED: (s) and (l)

when writin Keq expressions coefficents become

exponents in the Keq expression

Le Chatelier’s Principle

when stress is applied to a system at equilibrium, the system will react in such a way to relive the stress

when there is an increase in the concentration of a substance the system will

shift to consume the increasing concentration

when there is a decrease in the concentration of a substance by removing some amount the system will

shift to the side to replace/ produce more of the substance being removed

when there is an increase in pressure the system will shift to the side where

there is a SMALLER number of GASEOUS moles

when there is a decrease in pressure the system will shift to the side where

there is a GREATER number of GASEOUS moles

when there is an increase in temperature the system will shift to the side where

the added heat is consumed or the ENDOthermic reaction

when there is a decrease in temperature the system will shift to the side where

the heat will be generated or the EXOthermic reaction

endothermic reaction symbol

exothermic reaction symbol