3.2.3 equilibrium Flashcards
dynamic equilibrium
occurs when the forward and backward reactions are occurring at equal rates
concentrations of reactants and products stays constant and reaction is continuious
effect of temperature on equil
increasing > shits to endothermic (+) direction to try to reduce the temperature by absorbing heat
decreasing > shits to exothermic (-) direction to increase temperature
+ effect on yield
low temperatures
may give a higher yield but will also result in slow rates of reaction
effects of pressure on equilibrium
increasing pressure > side with fewer moles of gas to oppose the change & reduce the pressure
decreasing pressure > side with more moles of gas
if number of moles is same on both sides, then changing pressure will have no effect on position of equilibrium
high pressure
may give a higher yield & faster rate but expensive to maintain conditions
effect of concentration on equilibrium
I2 + 2OH- > I- + IO- + H2O
increasing OH- ion concentration causes equilibrium to shift to forward direction to remove OH- ions
equil shifts to right, giving higher yield of I- and IO-
adding H+ ions reacts with OH- and reduces their concentration so equil > left
effect of catalysts on equilibrium
no effect on position as it speeds up rate of forwards and backwards equally
haber process
N2 + 3H2 > 2NH3
450C
iron catalyst
200-1000 atm
contact process
stage 1: S + o2 > SO2 (g)
stage 2: SO2 + 0.5O2 > SO3
450C
1-2 atm
V2O5 catalyst
equilibrium constant
Kc = conc of products / conc of reactants
mol dm-3
