Le Chatelier's principle

Question 1

what is Le Chatelier’s principle?

Answer 1

If a reaction at equilibrium is subjected to a change in pressure, temperature, or concentration the position of equilibrium will move to counteract the change

Question 2

What happens to equilibrium if concentration is increased?

Answer 2

(change); concentration increased
(opposition); equilibria will shift to reduce concentration (move towards reactant/product with less concentration)
(yield); more of substance with less original concentration is produced

Question 3

What equilibria does Le Chatelier’s principle only work in?

Answer 3

only works in homogeneous equilibria (reactants and products in the same state)

Question 4

What happens to equilibrium if pressure is increased?

Answer 4

(change); increase pressure
(opposition); equilibrium will shift to side with fewer moles to try to reduce the pressure
(yield); increases yield of substance with fewer moles

Question 5

What happens to equilibrium if pressure is decreased?

Answer 5

(change); decrease pressure
(opposition); equilibrium will shift to side with the most moles of gas to try to increase the pressure
(yield); increases yield of substance with larger moles

Question 6

What happens to equilibrium if a catalyst is added?

Answer 6

catalysts have no effect on the position of equilibrium = will speed up the rate of the forward and backward reaction equally

= speeds up the rate at which equilibrium is reached but has no effect on yield

Question 7

What are the compromises made for reaction of ethanol?

Answer 7

• compromised high temp = although decreasing the temp would produce more product, a high temp is needed to maintain a faster rate of reaction
• compromised high temp = shifts equilibrium to side of product, rate of reaction increases, however, it is expensive to maintain high pressure environment
• use of a catalyst = speeds up rate of reaction