The Algebra of State Functions. The Helmholtz and Gibbs Functions
Juan H. Vera, Grażyna Wilczek-Vera · 2016
Until now, we have encountered four state functions of a system characterized by the measurable variables: absolute pressure, P ; absolute temperature, T ; and the composition of the system expressed by the number of moles of each compound present, n i . These state functions are the total volume, V ; the internal energy, U ; the entropy, S ; and the enthalpy, H . Two more state functions are used in thermodynamics. These are the Helmholtz function , 4.1 A = U − T S https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315399065/4741cd52-f3e4-43ff-9242-14456c3d0226/content/equ04_01.tif"/> and the Gibbs function , 4.2 G = H − T S https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315399065/4741cd52-f3e4-43ff-9242-14456c3d0226/content/equ04_02.tif"/>