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Definition of F

# Definition of F - Definition of F G H Suppose that F = U...

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Definition of F , G , H Suppose that F = U - στ . Then when we take the differential, we need to remember to use the product rule. We obtain: dF = dU - σ - τ Now, we can substitute in the Thermodynamic Identity to obtain: dF = - σ - p dV + μ dN Notice that F is a function now of τ , V , and N . By adding the term - στ , we were able to swap two of the variables, σ and τ . We call F the Helmholtz Free Energy, and we will soon see why it is useful. The quick mind will realize that we could define 6 such energies in total, by successively swapping all of the variables. It turns out that we'll only be interested in two more. The Enthalpy, H , swaps p and V . We write H = U + pV and obtain dH = τ + V dp + μ dN . We also define the Gibbs Free Energy by utilizing both of these swaps. Letting G = U + pV - τσ , we obtain dG = - σ + V dp + μ dN . We say that the energy of any of these types is a function of the variables that appear as

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Definition of F - Definition of F G H Suppose that F = U...

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