[19.2] the equilibrium constant Kp

Question 1

what happens should be considered with reactions involving gases?

Answer 1

• for gases, it is often more convenient to use the pressure of the gas rather than its concentration
• conc and pressure and proportional to one another and Kp has a direct relationship to Kc

Question 2

what is a mole fraction?

Answer 2

the mole fraction of a gas is the same as its proportion by volume to the total volume of gases in a gas mixture

Question 3

what is the equation to calculate mole fraction x(A)?

Answer 3

number of moles of A / total number of moles in gas mixture

Question 4

what must the sum of the mole fractions in a gas mixture equal to?

Answer 4

1

Question 5

what is partial pressure (p) of a gas?

Answer 5

the contribution that the gas makes towards the total pressure P

Question 6

what is the sum of the partial pressures of each gas equal to?

Answer 6

the total pressure

Question 7

how do you calculate partial pressure?

Answer 7

mole fraction × total pressure

Question 8

what is Kp?

Answer 8

the equilibrium constant for gas phase reactions

Question 9

how do you calculate Kp?

aA (g) + bB ⇌ cC (g) + dD (g)

Answer 9

p(C)ᶜ p(D)ᵈ / p(A)ᵃ p(B)ᵇ

never use square brackets for partial pressure - you may get zero marks