The Van t Hoff equation relates the change in the equilibrium constant, , of a chemical reaction to the change in temperature, T, given the standard enthalpy change, , for the process. The subscript  means "reaction" and the superscript  means "standard". It was proposed by Dutch chemist Jacobus Henricus van t Hoff in 1884 in his book Études de Dynamique chimique (Studies in Dynamic Chemistry). 
The Van t Hoff equation has been widely utilized to explore the changes in state functions in a thermodynamic system. The Van t Hoff plot, which is derived from this equation, is especially effective in estimating the change in enthalpy and entropy of a chemical reaction.