Kp [P2] PAPER 1

Question 1

How to calculate partial pressure?

Answer 1

partial pressure = mole fraction x total pressure

Question 2

how to calculate the mole fraction of a substance?

Answer 2

mole fraction of substance = moles of substance / total moles

Question 3

effect of a catalyst on the value of Kp of a reaction?

Answer 3

• no effect
• catalysts increase the rates of the forwards and backwards reactions equally

Question 4

Kp equation?

Answer 4

p = partial pressure of __ in the equilibrium mixture

Question 5

What affects the value of Kp?

Answer 5

temperature

Question 6

A reaction is endothermic. What happens to the value of Kp for this reaction if the temperature is increased?

Answer 6

• value of Kp increases
• equilibrium shifts to the right in the endothermic direction to oppose the increase in temperature, causing the partial pressures of [products] to increase, while the partial pressures of [reactants] decreases

Question 7

A reaction is exothermic. What happens to the value of Kp for this reaction if the temperature is increased?

Answer 7

• value of Kp decreases
• equilibrium shifts to the left in the endothermic direction to oppose the increase in temperature, causing the partial pressures of [reactants] to increase, while the partial pressures of [products] decreases

Question 8

A reaction is endothermic. What happens to the value of Kp for this reaction if the temperature is decreased?

Answer 8

• the value of Kp decreases
• equilibrium shifts to the left in the exothermic direction to oppose the decrease in temperature, causing the partial pressures of [reactants] to increase, while the partial pressures of [products] decreases

Question 9

A reaction is exothermic. What happens to the value of Kp for this reaction if the temperature is decreased?

Answer 9

• value of Kp increases
• equilibrium shifts to the right in the exothermic direction to oppose the decrease in temperature, causing the partial pressures of [products] to increase, while the partial pressures of [reactants] decreases

Question 10

Calculating the units of Kp?

Answer 10

Same as how Kc units are calculated, except using kPa, e.g.

Question 11

For a reaction, at 1050K, Kp = 762000Pa, and at 500K, Kp = 39400Pa.

Explain how this information can be used to deduce that the forward reaction is endothermic

Answer 11

• the value of Kp is higher at a higher temperature
• So, at a higher temperature, equilibrium must shift to the right

Question 12

given the Kp value of equation 1, what is the Kp of equation 2? Give the value and units.

Answer 12