Mole Fraction Equilibrium Constant
The equilibrium constant written in terms of the mole fractions of the reacting gases.
Formula / equation
Kx = Kp × p^(−Δn)
Unit
Dimensionless
In depth
Unlike Kp and Kc, the mole fraction constant depends on total pressure whenever the number of gas molecules changes during the reaction. This makes it a useful way of showing explicitly how total pressure shifts the composition of an equilibrium mixture.
Examples in the real world
Raising total pressure lowers Kx for the dissociation of PCl₅, driving the equilibrium back towards PCl₅.