Thermodynamics 10. Free energies A and G

Thermodynamics 10. Free energies A and G - work Important...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Thermodynamics 10. The Two Free Energies Read in text: Sections 3.5, 3.7, 3.8, 3.9 Problems: 1. 3.16a, p. 114 2. 3.17a 3. 3.18a ------------------------------------------------------------------------------------------------------ Introduce two state functions to monitor spontaneous processes in the SYSTEM. . Helmholtz free energy If V=constant and T=constant, introduce A = U – TS, Prove that dA<0 for spontaneous irreversible processes. A seeks a minimum Also prove dw non-exp =dA=dU-TdS=maximum non-expansion work Gibbs free energy If P=constant and T=constant, introduce G = H – TS Prove that dG<0 for spontaneous irreversible processes. G seeks a minimum Also prove dw non-exp. =dG=dH-TdS=maximum non-expansion
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: work Important question: What is free about the free energy? Important relations (under what conditions are these valid?) Function A(V,T) : dA=-PdV-SdT Function G(P,T) : dG= VdP-SdT Combined 1-st and 2-nd laws: dU= -pdV+TdS The variation of G with T and P: T G V P G = &amp; , P G S T G = - &lt; &amp; Plot G vs. T and P Variation of G with P (const. T) 2 1 2 1 ( ) ( ) ( ) P P G P G P V P dP = + For the ideal gas: 2 1 2 1 ( ) ( ) ln( / ) G P G P nRT P P = + Variation of G with T (const. P) Start from P G G H S T T G-= - = &amp; Derive the Gibbs-Helmholtz equation 2 P G H T T T = -&amp; (there are several other forms of the GH equation)...
View Full Document

Page1 / 2

Thermodynamics 10. Free energies A and G - work Important...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online