topic 4: chemical equilibrium Flashcards
explain what happens in an open chemical system
energy and matter move freely between the system and surroundings
explain what happens in a closed chemical system
energy can move between the system and surroundings but matter cant
explain what happens in an isolated chemical system
neither energy nor matter can move between the system and the surroundings
which of the 3 chemical systems is used in equilibrium reactions
closed
explain what is meant by dynamic equilibrium
a point where the forward and reverse reactions occur at the same rate
what can be stated about the reactants and products at dynamic equilibrium
at this point the concentrations of reactants and products remain constant butt they are rarely equal
explain what is meant by the equilibrium lying to the right
the forward reaction is favoured, and more product is made
explain what is meant by the equilibrium lying to the left
the reverse reaction is favoured and more reactant remains
what does le chatelier’s principle state
“if a system at equilibrium is subjected to change the system reajustes itself to counteract the change”
the three main factors afftecting an equilibriums position
•concentration
•temperature
•pressure
consider: A+2B ⇌C+D
what happens if the concentration of A or B is increased
•equilibrium shifts to bring [A/B] back down
•more A+B react so forward reaction is favoured
•equilibrium shifts right (more product)
consider: A+2B ⇌C+D
what happens if the concentration of A or B is decreased
•equilibrium shifts to bring [A/B] back up
•more C+D react to make more A+B
•reverse reaction is favoured (more reactant)
•equilibrium position shifts left
consider: A+2B ⇌C+D
what happens if the concentration of C or D is increased
•equilibrium shifts to bring [C/D] back down
•more C+D is converted back into reactants
•reverse reaction is favoured (more reactant)
•equilibrium position shifts left
consider: A+2B ⇌C+D
what happens if the concentration of C or D is decreased
•equilibrium shifts to bring [C/D] back up
•more A+B is converted into products
•forward reaction is favoured (more product)
•equilibrium position shifts right
if the forward reaction us exothermic what will the reverse be
endothermic
in an exothermic reaction what happens the the equilibrium when there is temperature increase
•system shifts to bring the temp back down
•reverse reaction will be favoured to absorb the additional heat
•equilibrium shifts left, favouring reactants
in an exothermic reaction what happens the the equilibrium when there is temperature decrease
•system shifts to raise the temp
•favours the reaction that releases heat- the forward exothermic reaction
•equilibrium shifts right, favouring products
describe the result of a pressure increase on this equilibrium
A+2B ⇌C+D
3 moles-2 moles
•equilibrium shifts to decrease the pressure (less molecules)
•shifts to the right, favouring the forward reaction
describe the result of a pressure decrease on this equilibrium
A+2B ⇌C+D
3 moles-2 moles
•equilibrium shifts to increase the pressure (more molecules)
•shifts to the left, favouring the reverse reaction
explain what happens in an equilibrium with a catalyst
a catalyst doesn’t effect the position of an equilibrium it just decreases the time taken for a reaction to reach equilibrium
