Avoid Common Pitfalls When Using Henry's Law

Henry’s law and the Henry’s constant are widely used in chemical and environmental engineering. Unfortunately, many people do not appreciate that the Henry’s “constant” is not a true constant, but instead has a significant non-linear temperature dependence. Ignoring this temperature dependence can lead to serious inaccuracies. This article discusses the temperature dependence of the Henry’s constant and suggests ways of estimating this dependence when data are limited or not available. It also briefly discusses other common pitfalls to be avoided when using Henry’s law. The focus is on dilute aqueous systems, such as those found in environmental applications, but much of the information is also appropriate for other applications.