3: equilibrium, Le Châtelier’s Principle

Question 1

two conditions of equilibrium

Answer 1

1. rates are equal
2. constant concentration

Question 2

what is included/not includued in Kc and Qc

Answer 2

in the clurb: aqueous, gases
not in the clurb: solids, liquids

Question 3

Kc»1

Answer 3

equilibrium will lie to the right and favour the products

Question 4

Kc«1

Answer 4

equilibrium will lie to the left and favour the reactants

Question 5

Kc = 1

Answer 5

50/50, equally favoured

Question 6

Homogenous

Answer 6

same states in reaction

Question 7

heterogeneous

Answer 7

different states in reaction

Question 8

Qc>Kc

Answer 8

system will move to the left (more reactants, less product) to reach a new equilibrium position

Question 9

Qc<Kc

Answer 9

system will move to the right (less reactants, more products) to reach a new equilibrium position

Question 10

Qc=Kc

Answer 10

at equilibrium

Question 11

Le Châtelier’s Principle

Answer 11

If an external stress is applied to a system at equilibrium, the system will adjust itself in such a way as to partially offset the stress as the system reaches a new equilibrium position

Question 12

Possible external stresses

Answer 12

• change in concentration
• change in pressure and/or volume (affects only gases)
• change in temperature (effects Kc)
• addition of a catalyst (does not shift equilibrium position, but will speed up the overall reaction by reducing activation energy)

Question 13

relationship between volume and pressure

Answer 13

as volume increases, pressure decreases

Question 14

which way does equilibrium shift after increasing or decreasing pressure

Answer 14

increase pressure (less volume): side with least mols of gas
decreasing pressure (more volume): side with most mols of gas

Question 15

what effect on equilibrium does an inert gas have

Answer 15

no effect

Question 16

what effects Kc?

Answer 16

only temperature
eq shifts to left = decrease Kc
eq shifts to right = increase Kc