Heavy Wall Glass Le Chatelier Flask, For Chemical Laboratory, Capacity: 1000 ml

Le Chatelier–Braun principle analyzes the qualitative behaviour of a thermodynamic system when a particular one of its externally controlled state variables, say L, changes by an amount ΔL, the 'driving change', causing a change δiM, the 'response of prime interest', in its conjugate state variable M, all other externally controlled state variables remaining constant. The response illustrates 'moderation' in ways evident in two related thermodynamic equilibria. Obviously, one of L, M has to be intensive, the other extensive. Also as a necessary part of the scenario, there is some particular auxiliary 'moderating' state variable X, with its conjugate state variable Y. For this to be of interest, the 'moderating' variable X must undergo a change ΔX≠0 or δX≠0 in some part of the experimental protocol; this can be either by imposition of a change ΔY, or with the holding of Y constant, written δY=0. For the principle to hold with full generality, X must be extensive or intensive accordingly as M is so. Obviously, to give this scenario physical meaning, the 'driving' variable and the 'moderating' variable must be subject to separate independent experimental controls and measurements.