Chemical Equilibria, Le Chatelier's and Kc (All 3) Flashcards
Define dynamic equilibrium
- the forward and backward reactions proceed at equal rates
- the concentrations of reactants and products are the same.
State Le chatelier’s principle
the position of the equilibrium will shift to oppose a change to it.
CO + H2O <–> CO2 +H2
If the conc of CO is INCREASED…
equilibrium shifts right
to oppose increase in conc of CO
yield of CO2 + H2 increases
CO + H2O <–> CO2 +H2
If the conc of CO is DECREASED…
equilibrium shifts to the left
to oppose decrease in conc of CO
yield of CO + H2O increases
2NO2 <–> N2O4
If pressure INCREASED…
equilibrium shifts right (fewer mole of gas)
to oppose increase in pressure
yield of N2O4 increases
2NO2 <–> N2O4
If pressure DECREASED…
equilibrium shifts left (more moles of gas)
to oppose decrease in pressure
yield of NO2 increases
How does volume affect pressure?
decrease in volume increases the pressure
increase in volume decreases the pressure
CH4 +H2O <–> CO + 3H2
delta H = -206
If temp DECREASED…
forward reaction is exothermic
equilibrium will shift right to oppose decrease in temp
yield of CO + H2 increases
CH4 +H2O <–> CO + 3H2
delta H = -206
if temp INCREASED…
backward reaction in endothermic
equilibrium will shift left to oppose temp increase
yield of CH4 + H2O increases
When a catalyst is added to a reversible reaction…
the rate of both forward and reverse reactions increases equally
no change in position of equilibrium
dynamic equilibrium is reached faster.
Compromise conditions (6 marker)
catalyst;
does not affect the yield
increases the rate of both equally
less time taken to reach equilibrium
pressure;
higher pressure = higher yield
faster rate
high = more expensive
temperature;
lower temp = higher yield
faster rate
low = less expensive
Equation for Kc
Kc = [products] / [reactants]
What effects the value of Kc?
Only TEMPERATURE
Units for Kc?
mol dm^-3
If all equilibrium amounts given use..
Kc expression
