Shreder Equation

a mathematical equation relating the solubility of a crystalline body x_T at a temperature T (in °K) to its heat of melting ΔH_m (in cal/mole) and melting point T_m:

where R is the gas constant; ΔH_m is taken as constant in the interval T_m–T. The rigorous application of the Shreder equation is limited to ideal solutions. By constructing curves for the temperature dependence of the solubility of a solid phase of each of the components of a binary system using the Shreder equation, it is possible to find the eutectic point and to obtain the solubility diagram.

The Shreder equation was derived in 1890 by I. F. Shreder (Schröder). It is also known as the Shreder logarithm and the Shreder-Le Chätelier equation. (H. Le Chätelier previously had obtained an equation for solubility as a function of temperature in differential form and, using this expression, derived an equation similar to the Shreder equation in 1894.)