11: Equilibrium II

Question 1

Deduce an expression for Kp for the reaction:
H₂(g) + I₂(g) ⇋ 2HI(g)

Answer 1

Kp = p(HI)² / p(H₂)p(I₂)

Question 2

How do you calculate the partial pressure from the moles of a substance in a system in equilibrium?

Answer 2

Mole fraction = moles of substance / total moles

Partial pressure = mole fraction x total pressure

Question 3

Describe the effect of changing temperature on the equilibrium constant, for both exothermic and endothermic reactions.

Answer 3

Exothermic reaction: Increasing the temperature decreases the equilibrium constant.

Endothermic reaction: Increasing the temperature increases the equilibrium constant.

Question 4

What are 3 factors which do not affect the value of the equilibrium constant?

Answer 4

Concentration
Pressure
Addition of a catalyst