Pressure Equilibrium Constant
The equilibrium constant for a gaseous reaction expressed in terms of partial pressures.
Formula / equation
Kp = p_C^c p_D^d / p_A^a p_B^b
Unit
Various
In depth
Kp is preferred for gas-phase work because partial pressures are measured more directly than concentrations. As with Kc, condensed phases are excluded from the expression, and the value depends only on temperature.
Examples in the real world
For the ammonia equilibrium, Kp = p(NH₃)² / (p(N₂) × p(H₂)³) with pressures in bar.