By Little Pro on 2016-01-13 Views: Update:2018-02-09
Henry's law constant (HLC) is a measure of the concentration of a chemical in air over its concentration in water. Henry’s Law constant for a chemical is usually expressed in one of two ways:
H = Concentration of chemical in air/Concentration of chemical in water (unitless) or H'= Liquid vapor pressure/chemical solubility (atm-m3/mol)
You can often find it in the section 9 of a safety data sheet (SDS).
The Henry's Law Constant (LC) is a key important parameter for determining a chemical’s environmental distribution behavior. It reflects the relative volatility of a particular substance and represents a major property to describe fate and transport modeling in environmental risk assessment.
Chemical substances with high HLC values will volatilize from water into air and be distributed over a large area. Chemical substances with low HLC values tend to persist in water and may be adsorbed onto soil or sediment.