Equilibria Flashcards
what are reversible reactions
when reactions can go forward or backwards
forward reaction concentration
Initially the reactants are used up quickly but then slow as their concentration drops
Backward reaction
Initially reactants are reformed slowly but then speed up as the concentration of products increases
equilibrium is when…
the rate of reaction of the forwards reaction is at the same rate of the backwards reaction
only occurs in closed systems
Le chatelier’s principle
if a reaction at equilibrium is subject to change, the position of the equilibrium will move to counteract that change
Le chatelier’s (TEMPERATURE)
- if we increase the temperature the equilibrium position will shift to reduce the temperature
- INCREASING temp= equilibrium SHIFTS TO THE ENDOTHERMIC direction, to try decrease the temp
- DECREASING TEMP= equilibrium SHIFTS TO THE EXOTHERMIC direction, to try increase the temp
if enthalpy change is NEGATIVE…
then the foward reaction is EXO
do catalysts have an effect in equilibrium
NO
as it has NO effect on the yield
making ethanol CONDITIONS
why 300
why is increasing pressure expensive
phosphoric acid catalyst ( H3PO4)
300 degrees celcius
60atm
- 300 degrees is a compromise between yield and rate.
- high pressure environments are expensive due thicker and more robust pipes needed. There is a compromise between yield, speed and cost
Kc equilibrium constant
IF 2A+B-> 2C+D
then Kc= {C}^2{D}/{A}^2{B}
MOLAR RATIO for products and reactants
Kc concentration
products= increase reactants= decrease
what is the only unit that Kc can be found in
CONCENTRATION
so convert using amount of substance equations if you have to
what affects Kc
ONLY TEMPERATURE
if the temperature change causes equilibrium to shoft to the RIGHT Kc will INCREASE
if temperature change causes equilibrium to shift to the LEFT TEMPERATURE DECREASES
