m3 - equilibrium Flashcards
examples of reversible processes
changing state eg freezing
the Haber process - producing ammonia (iron catalyst)
SO2 + O2
how/where is dynamic equilibrium reached (3 things)
closed system - nothing can get in or out
rate of forward reaction = rate of reverse reaction
when the conc of reactants = products
what 3 things change position of equilibrium
concentration
pressure (gases)
temperature
effect of concentration on equilibrium
increase reactant conc, equilibrium favours forward reaction (to get rid of these new reactants), moves to the right
increase product conc, equilibrium favours backward reaction, moves to the left
effect of temp on equilibrium 
increasing temp (means more energy so want to take it away) - favoured by endothermic reactions
decreasing temp (taking energy away, want to put it back) - favoured by exothermic reactions
effect of pressure on equilibrium (only in gas reactions)
increasing pressure favours reaction with a decrease in total no of moles (shifts to side with less moles)
decreasing pressure favours reactions with an increase in total no of moles
equilibrium constant reaction (Kc)
[C^moles] x [D^moles]
—————————————
[A^moles] x [B^moles]
Haber process pressure and temperature
200atm
450°C
how does catalyst affect position of equilibrium
it doesn’t, it increases rate of forward and backward reactions by the same amount
compromise between rate of reaction and yield
want a relatively good rate and yield
eg if yield was only taken into account, rate may be too low that the reaction is unuseful
also safety, too high pressure may not be safe
also expensive
what factors effect Kc and Kp (equilibrium constant)
temperature only
(conc, pressure and catalysts only affect rate not position)
how to work out mole fraction
molecules of X
———————
total molecules
partial pressure equation
partial pressure of X = mole fraction x total pressure
(mole fraction = molecules of X / total molecules)
how to work out Kc
conc products
———————
conc reactants
2 moles of something means you’d square it
Kc and Kp expressions in homogenous vs heterogeneous reactions
normal in homo
in herero: concentration of any solids aren’t counted in the equation
