3.1.6 chemical equilibria (just things dont know ) Flashcards
in a reversible reaction at equilibrium
- the forward + reverse reactions proceed at equal rates
- the concentrations of reactants and products remain constant
dynamic equilibrium
the point where the forward and backward reaction are happening at the same rate , the conc of reactants and products is constant and this can only happen in a closed system
closed system
on in which none of the reactants or products escape from the rxn mixture
open system
matter and energy can be lost to the surroundings
homogenous system
system where all the chemicals are in the same place
le chateliers principle
if a system at equilibrium is disrupted , the position of equilibrium will shift in the direction that counteracts / lessens the effect of change
effect of increasing temp
- equilibrium shifts to favour the endothermic reaction
- as the excess heat needs to be removed from the system to counteract / lessen the effect of the initial increase
- it will increase the yield of the endothermic products
effect of decreasing temp
- equilibrium shifts to favour the exothermic reaction
- as heat needs to be gained to counteract / lessen the effect of reduced temperature and an exothermic reaction releases heat
- it will increase the yield of the exothermic products
effect of increase in conc of reactants
- equilibrium shifts to favour the reaction that produces / moves right
- to get rid of the extra reaction by forming more product as more molecules are available to react
- it will increase the yield of the products
effect of decrease in concentration of reactants
- equilibrium shifts to favour the reaction that produced reactants / moves left
- to counteract the effect of less reactants
- it will increase the yield / concentration of the reactants
effect of increasing pressure
- equilibriums shifts to favour the side with fewer moles
- this will help to release the build up in pressure and decrease the pressure
- it will increase the yield of the products on this side of the rxn
effect of decreasing pressure
- equilibrium shifts to favour the side with more moles
- pressure has been lost
- the yield of the products on this side of the rxn will be increased
equilibriums rxns in industry
- in industry they remove the products so that equilibrium shifts to right so more yield of products is made
- a compromise is made as a low temp gives food yield but slow rate , high temp would have faster rate of rxn . so a compromise is made
- a high pressure would be ideal as equilibrium would shift to the product side however it’s expensive
dynamic graphs
if Kc is large / greater than 1
equilibrium lies to the right as product concentration is greater than reactant concentration
if Kc is small / less than 1
equilibrium lies to the left as reactant conc is greater than product conc
if Kc is greater than 10^10
reaction is going to completion
effect on kc if more reactants (result of change in temp)
Kc decreases as in equation reactants are on the bottom and a larger denominator results in a lower Kc
effect on kc if more products (result of change in temp)
Kc increased as in equation products are on the top and a larger numerator results in a higher Kc
exothermic rxn
increase in temp = Kc decreases as equilibrium shifts in endo direction
decrease in temp = Kc increases as equilibrium shifts in exo direction
endothermic rxn
increase in temp = Kc increases as equilibrium shifts in endo direction
decrease in temp = Kc decreases as equilibrium shifts in exo direction
equilibrium law
