In the history of thermodynamics, Thermodynamik chemischer Vorgänge (Chemical thermodynamic process) is a sequence of three papers (1882–1883) written by German physicist Hermann von Helmholtz. It is one of the founding papers in thermodynamics, along with Josiah Willard Gibbs 's 1876 paper " On the Equilibrium of Heterogeneous Substances ". Together they form the foundation of chemical thermodynamics as well as a large part of physical chemistry.