Entropy of Mixing (3) S.J.T.U. Phase Transformation and Applications The molar fraction of ideal gas a. V。+y-n。+n2=1 na Xa The entropy of mixing per mole of the mixture: S=x,Rnt'+,Rn+业 Va Va V =-R[xlnx。+xlnx] In general,the entropy of mixing of n ideal gases is: H 1=n ASm=-∑xlnx i=1 SJTU Thermodynamics of Materials Spring2010©X.J.Jin Lecture 6 Property Relation IlPhase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2010 © X. J. Jin Lecture 6 Property Relation II Entropy of Mixing (3) The molar fraction of ideal gas a. Va VT a a a b a a b n x n n V V V 1     Vb   a a b b b a b b a a b mix a R x x x x V V V x R V V V S x R ln ln ln ln         In general, the entropy of mixing of n ideal gases is: The entropy of mixing per mole of the mixture:       i n i mix i i S x x 1 ln