DN 5). Equilibria Flashcards
equilibria is …. (4 conditions)
dynamic process
1) . both reactions are taking place simultaneously
2) . at the the same rate
3) . all the reactants and products are present / closed system
4) . all reactants and products concentrations remain the same / are constant
what is Le Chatelier’s principle
if you apply a change to a system in equilibrium, the equilibrium shifts to oppose the change
explaining the change to equilibrium when
- temperature increase
state which reaction is exothermic
state what happens generically when temperature is increased: as temperature increases, equilibrium will shift to decrease the temperature therefore moves in endothermic direction
state what this means for the particular reaction (left or right hand shift)
explaining the change to equilibrium when
- pressure increases
state where there are more moles of gas
state what happens generically when pressure increases: as pressure increases, equilibrium moves to decrease the pressure by shifting to the side with the fewer moles
state what this means for the particular reaction
explaining the change to equilibrium when
- catalyst is added
alters the rate of the forward and backwards reaction by the same amount so equilibrium is reached faster
BUT EQUILIBRIUM WILL REMAIN IN THE SAME PLACE
equilibrium constants are …measures
quantitative
homogeneous systems are where….
all species are in the same state
Kc =
[products] / [reactants]
how to work out units of Kc
moldm^-3 for each species then cancel accordingly
with Kc what happens to big numbers
they turn to indicies
Kc is ….. at constant temperature
constant
what happens when Kc is bigger than 1
more products than reactants
how to work out changing temperatures effect on Kc
draw table of temp vs Kc
as temp increases Kc …… (if decrease then products are decreasing then vice versa)
therefore equilibrium has shifted to …. (use increase of heat = shift in endothermic direction to help work out)
concentrations effect on Kc
value of Kc will not change as is at a constant temperature
BUT [] will change individually
catalyst effect on Kc
no change to Kc (but will reach equilibrium faster)
