The Kp in the study of chemistry is an equilibrium constant of both heterogeous and homogeneous gaseous reactions, according to ChemGuide. Value is determined by the partial pressures of the gases inside a closed system.
ChemGuide states that the Kp constant does not account for the concentrations or partial pressures of single components such as solids or liquids, nor does it have any units of measure. The Kp value can also be obtained from the Kc equilibrium constant. According to the University of California, Davis, this Kc concentration equilibrium represents the temperature, change in the moles and gas constant value.