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Unformatted text preview: Lecture 21 1 Liquidliquid Solutions – Ideal and Miscible (Chpt 24.14) We will extend our knowledge of phase equilibria to multicomponent systems. We must first consider partial molar quantities (initially for two components). ( 29 1 2 , , , , , so partial molar Gibbs Energy i j j j j T P n G T P n n G G n μ & & = = & The chemical potential of one component in a multicomponent system is its partial molar Gibbs energy. We can, in principle, define partial molar quantities for other thermodynamic quantities: , , , , . i k i j j k j k T P n T P n S V S V etc n n j j & = = & Lecture 21 2 Now at constant T, P (typical experimental conditions): 1 1 2 2 dG dn dn μ μ = + Note:G and n j are extensive thermodynamic variables. If we are adding components to our system, or adjusting the size of our system: 1 1 2 2 , dn n d dn n d dG Gd λ λ λ = = = 1 1 1 1 1 2 2 1 1 2 2 at constant T and P Gd n d n d G n n λ μ λ μ λ μ μ = + = + We can do the same with another extensive variable: 1 1 2 2 V V n V n = + Fig 24.1 i Note: V can vary with mole fraction Lecture 21 3 From our definitions: G H TS = j i i taking at constant T,P,n n i i i H TS μ= Similarly: dG=SdT+VdP j i i taking at constant T,P,n n i i i d S dT V dP μ= + Partial molar quantities, although intensive variables, behave just like...
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 Spring '08
 JamesLis
 Thermodynamics, pH, Vapor pressure, RT ln, µi vap dni vap, vap dni vap

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