equilibria

Question 1

what is dynamic equilibrium?

Answer 1

dynamic equilibrium exists in a closed system where the rate of the forwards reaction is equal to the rate of the reverse reaction, and the concentrations of reactants and products remain constant

Question 2

why does adding a catalyst not affect the position of equilibrium?

Answer 2

the rate of the forwards and reverse reaction is increased equally so the position does not change

Question 3

Le Chatelier’s Principle

Answer 3

when a system in equilibrium is subject to an external change, the system readjusts itself to minimise the effect of that change

Question 4

Effect of concentration changes on equilibrium

Answer 4

increase in conc. of products = p.o.e shifts to reactant side so more reactants formed
increase in conc. of reactants = p.o.e shifts to product side so more products formed

Question 5

effect of temperature changes on equilibrium

Answer 5

temp increases = p.o.e shifts to endothermic side (so temp decreases)
temp decreases = p.o.e shifts to exothermic side (so temp increases)

Question 6

effect of pressure on equilibrium

Answer 6

increase pressure = shift towards side with fewer gas moles
decrease pressure = shift towards side with more gas moles

Question 7

Kc equation

Answer 7

2A + 3B <—> C + 4D
[products]/[reactants]
[C][D]^4 / [A]^2[B]^3

Question 8

predictions from magnitude of Kc

Answer 8

Kc value of 1 = p.o.e halfway between reactants and products
Kc < 1 = p.o.e towards reactants
Kc > 1 = p.o.e towards products