Gravochemical potential

The chemical potential now includes any such effects, and one refers to the gmvochemicalpotential, the electrochemical potential, etc. For example, if the system consists of a gas extending over a substantial difference in height, it is the gravochemical potential (which includes a tenn m.gh) that is the same at all levels, not the pressure. The electrochemical potential will be considered later. 

The combination (z) + Mtgz occurs so frequently in this type of analysis that it is assigned a new symbol, termed the gravochemical potential. 

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