topic 10+ 11: eqm 1 + 2 Flashcards
what is dynamic equilibrium
- forwards and backwards reactinos occur at equal rates
- concentrations of reactants and products remain constant
le chatelier’s principle
if a change happens the equilibrium will shift to try to reverse it
increase in temp effect on eqm?
- shifts equilibrium in the ENDOTHERMIC direction
difficulty with temp equilibrium
- low temperatures can give higher yield
- but slower rate
- so use a compromise temperature, OR LOW TEMP AND CATALYST
Effect of pressure on equilibrium
- causes equilibrium to shift to the side with FEWER MOLES OF gas
in industry, high temperatures and pressures are…
- EXPENSIVE (equipment and energy costs)
effect of concentration on equilibrium
- increase in concentration of one thing means the POE will shift in the opposite direction on this
effect of catalysts on equilibirum
NO EFFECT
- as speeds up rate of forwards and backwards reactions by same amount
- only speeds up rate at which equilibrium is achieved
advantage of using a catalyst?
- speeds up rate
- SO CAN USE LOWER TEMP AND PRESSURES
- lower energy costs
- lower equipment costs
strange way to increase yield?
- reversible reactions
- so recycle unreacted reactants
Kc expression
eg
A + 2B = 3C
Kc = [C]^3 / [A][B]^2
HOMOGENEOUS equilibirum
reactants and products all in same phase
heterogeneous equilibrium
reactants and products not all in same phase
in heterogeneous equilibrium, which do you include in Kc
GASES
- no solids or liquids
when do you include water in Kc
- when water is a REACTANT, not a solvent
- otherwise its concentration remains constant so isnt included
what can change Kc
ONLY THE TEMPERATURE!!!!!!!!