Equilibria
Le Chatelier's Principle
Concentration
Pressure
Temperature
The Equilibrium Constant
Compromise Reaction Conditions
Increasing the temperature shifts the equilibrium to the endothermic direction to absorb the heat.
Decreasing the temperature will shift the equilibrium in the exothermic direction to produce more heat.
Increasing the concentration of a product causes the equilibrium to shift towards the reactants to remove the product.
Increasing the concentration of a reactant, the equilibrium shifts towards the products, to remove the reactants.
Increasing the pressure shifts the equilibrium towards the side with fewer gas molecules, to reduce the pressure.
Decreasing the pressure shifts the equilibrium to the side with more gas molecules to raise the pressure
Production of ethanol
Compromise reaction conditions produce the highest yield for the lowest cost. For example, the production of ethanol, as it is an exothermic reaction, so a lower temperature would increase the yield, but would decrease the rate. Also increasing the pressure would increase the rate, but would also increase costs.
60 atmospheres
300 degrees
aA + bB ⇌ dD + eE
Kc = ([D]d[E]e)/([A]a[B]b)
Kc is the equilibrium constant
Factors affecting Kc
Temperature
Changing the temperature will change the Kc. For an exothermic reaction, increasing the temperature reduces the value of Kc. For an endothermic reaction, increasing the temperature increases the value of Kc.
Concentration
Changing the concentration does not affect the Kc
Pressure
Changing the pressure does not affect the Kc