3.1.10 Equilibrium Constant Kp For Homogenous Systems Flashcards
What is kp?
Kp is an equilibrium constant based on partial pressures.
It tells you the ratio of products to reactants in a reaction at equilibrium.
How do we write the kp expression?
In the reaction:
aA + bB ⇌ cC + dD
Kp = p(C)^c p(D)^d | products
÷ | ÷
. p(A)^a p(B)^b | reactants
(A) = concentration of A in moldm^-3
a = number of moles of A
p = partial pressure
( ) instead of [ ] (will be penalised)
What do partial pressures add up to?
They add up to the total pressure.
What should the mole fractions add up to in an equilibrium?
They should add up to 1.
How do you calculate the mole fraction?
Mole fraction = moles of the desired gas
÷
total number of moles
How do you calculate the partial pressure of a desired gas?
Partial pressure = mole fraction of desired gas x total pressure
