n always involves products minus reactants.We have seen that the (apparent) units of the equilibrium constant depend on the specific reaction. For example, for the reaction H2(g) + F2(g) 2HF(g)the units of K and Kp can be found as follows: K = CHF2/[(CH2)(CF2)] = (mol/L)2/[(mol/L)(mol/L)] no units Kp = PHF2/(PH2)(PF2) = (atm)2/[(atm)(atm)] no unitsNote that in the above discussion we used the term “apparent units” when referring to equilibrium constants. This term was used because the theoretical foundation for the concept of equilibrium based on thermodynamics includes a reference state for each substance, which always cause the units of concentration or pressure to cancel.