Gas Equilibria and Kp

Question 1

What is partial pressure

Answer 1

In a mixture of gases, each individual gas exerts its own pressure - this is partial pressure

Question 2

What is the total pressure of a gas mixture?

Answer 2

The total pressure of a gas mixture is the sum of all the partial pressures of the individual gases

Question 3

What is a mole fraction?

Answer 3

A mole fraction is the proportion of a gas mixture that is made up of a particular gas

Question 4

What are the two formulas involving mole fractions?

Answer 4

1. Mole fraction of a gas in a mixture = number of moles of gas / total number of moles of gas in the gas mixture
2. Partial pressure of a gas = mole fraction of gas x total pressure of the mixture

Question 5

What is Kp?

Answer 5

Kp is the equilibrium constant for a reversible reaction where all the reactants and products are gases

Question 6

What is the expression for Kp?

Answer 6

Kp = (pD)d (pE)e / (pA)a (pB)b

Question 7

How is Kp affected by temperature?

Answer 7

Kp is only valid for one particular temperature. Changing the temperature changes how much product is formed at equilibrium. This changes the mole fractions of the gases present, which changes the partial pressures.

Question 8

Does changing pressure affect Kp?

Answer 8

Changing pressure doesn’t affect the value of Kp - the quilibrium will shift to keep it the same

Question 9

Will a catalyst affect Kp?

Answer 9

Adding a catalyst won’t affect Kp - it gets the system to reach equilibrium faster