The relationship that defines the partition of a soluble or partially soluble species between the gas and solution phases. It is often represented as H_c. It is the relationship of species dissolving but not reacting in solution to those in equilibrium in the gas phase. The equation used for this is: = *. H_c is the Henry's Law Constant. This may be regarded as a measure of the molecules in a gas to those dissolve in solution, and this relationship is temperature dependent. C_g and C_aq are the concentrations or partial pressure of species C in gas and aqueous solution, respectively.