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Flashcards in 6 equilibria Deck (19):

equilibrium mixture

the mixture of reactants and products formed when a reversible reaction is allowed to proceed in a closed container until no further change occurs. the forward and backward reactions are still proceeding but at the same rate


dynamic equilibrium

a situation in which the composition of a constant concentration reaction mixture does not change because both forward and backward reactions are proceeding at the same rate


closed system

where the reactants and products can't escape (doesn't have to be sealed)


reversible reaction at equilibrium

the forward and backward reactions proceed at equal rates & conc of reactants and products remain constant


chemical equilibrium

the state in which both reactants and products are present in concentrations which have no further tendency to change with time - usually, this state results when the forward reaction proceeds at the same rate as the reverse reaction


Le Chatelier's principle

"if a change occurs to a system in dynamic equilibrium, the position of equilibrium shifts in a direction to oppose the change"
- doesn't say how far the equ moves so cannot predict quantities involved but can predict effect of temp, press and conc on equ position in homogeneous reactions



a reaction in which an atoms or group of atoms is replaced by another



a reaction in which an atom or group of atoms is removed from a reactant/starting material


chemical feedstock

the starting materials in an industrial chemical process


homogeneous system

where all the reactants and products are in the same phase e.g. all liquids


equilibrium constant

Kc - a number that expresses the relationship between the amounts of products and reactants present at equilibrium in a reversible chemical reaction at a given temperature


equilibrium law expression

Kc = conc of products / conc of reactants


macroscopic properies

properties such as density, concentration, colour, pressure - properties that do not depend on the total quantity of matter


concentration of a solution

the number of mole of solute dissolved in 1dm3 of solution


conditions for equilibrium (4)

1. closed system
2. equ approached in either direction (from l or vapor)
3. dynamic process-reached when rates of the 2 processes are the same
4. equ reached when macroscopic props of system do not change w time


effect of conc on equilibrium

if you increase conc of one of the reactants, the equ will shift to reduce the conc of this reactant


effect of pressure on equilibrium

if you increase the pressure, the equ will shift to decrese the pressure


effect of temp on equilibrium

if you increase the temp, the equ will shift to cool the system down (endothermic)


effect of catalyst on position of equlibrium

no effect - only affects rate at which equ is reached