van der Waals equation

The van der Waals equation is an equation of state that relates the pressure, molar volume, and temperature in fluids. It describes both the liquid and gas states. It was the first successful thermodynamic model to treat fluids as being composed of molecules with finite size and with intermolecular interactions.

The equation is named after Dutch physicist Johannes Diderik van der Waals, who first derived it in 1873 as part of his doctoral thesis. Van der Waals based the equation on the idea that fluids are composed of discrete particles, which few scientists believed existed. However, the equation accurately predicted the behavior of a fluid around its critical point, which had been discovered a few years earlier. Its qualitative and quantitative agreement with experiments ultimately cemented its acceptance in the scientific community. These accomplishments won Van der Waals the 1910 Nobel Prize in Physics. Today the equation is recognized as an important model of phase change in fluids.