华东理工大学：《物理化学》课程教学课件（讲稿，英文版）07 Chapter 7 Simple mixtures.pdf_大学文库

版权所有：华东理工大学物理化学教研室 2 The chapter begins by developing the concept of chemical potential to show that it is a particular of a class of partial molar quantities. Then it explores how the chemical potential of a substance is used to describe the physical properties of mixture. The underlying principle is that at equilibrium the chemical potential of a species is the same in every phase. 7. Simple mixtures

版权所有：华东理工大学物理化学教研室 3 The thermodynamic description of mixtures 7.1 Partial molar quantities 7.2 The thermodynamics of mixing 7.3 The chemical potentials of liquid The properties of solutions 7.4 Liquid mixtures 7.5 Colligative properties Activities 7.6 The solvent activity 7.7 The solute activity 7. Simple mixtures

版权所有：华东理工大学物理化学教研室 4 1) Partial molar volume When the composition of the mixture is changed by the addition of dnA of A and dnB of B, the total volume of the mixture changes by 7.1 Partial molar quantities B B , A A , d d d B A n n V n n V V nTp nTp ⎟⎟⎠⎞ ⎜⎜⎝⎛ ∂∂ + ⎟⎟⎠⎞ ⎜⎜⎝⎛ ∂∂ = = + ddd nVnVV BBAA VA and VB are the partial molar volumes, they vary with composition

版权所有：华东理工大学物理化学教研室 5 Once the partial molar volumes of the two components of a mixture at the composition (and T) of interest are known, we can state the total volume, V, of the mixture by using = + VnVnV BBAA 7.1 Partial molar quantities

版权所有：华东理工大学物理化学教研室 6 • The determination of partial molar volume 7.1 Partial molar quantities With particular values of the parameters A, B, and C, then the partial molar volume of A at any composition could be obtained from A A , A 2CnB n V V nTp B += ⎟⎟⎠⎞ ⎜⎜⎝⎛ ∂∂ = J ', J nTp n V V ⎟⎟⎠⎞ ⎜⎜⎝⎛ ∂∂ =

版权所有：华东理工大学物理化学教研室 7 The determination of partial molar volume 7.1 Partial molar quantities B 2 A B AA B )1( n CnA n VnV V +− = − = The partial molar volume of the second component is obtained from = + VnVnV BBAA

版权所有：华东理工大学物理化学教研室 8 7.1 Partial molar quantities The molar volume: the volume that 1 mol substance occupies, which is always positive. The partial molar volume: the contribution of 1 mol of a component to the volume of the mixture at a specific T and p, which may be positive or negative. The determination of partial molar volume

版权所有：华东理工大学物理化学教研室 9 Partial molar quantities The concept of a partial molar quantity can be extended to any extensive state function. Let X denote any extensive properties of a system that contains K components 7.1 Partial molar quantities The change in X When dT, dp, dni ) ,( 21 nnnpTXX K = ⋅⋅⋅ ∑ = ≠ ⎟⎟⎠⎞ ⎜⎜⎝⎛ ∂∂ + ⎟⎟⎠⎞ ⎜⎜⎝⎛ ∂∂ ⎟ + ⎠⎞ ⎜⎝⎛ ∂∂ = Ki np nT npT n nX p pX T TX X ij 1 i , i , , d d d d j j

版权所有：华东理工大学物理化学教研室 10 7.1 Partial molar quantities Definition npT ij i i n X X ≠ ⎟⎟⎠⎞ ⎜⎜⎝⎛ ∂∂ = , def X and ni are extensive properties, and they are independent of the total quantities in systems; however, the partial molar quantities, Xi , is intensive property. ∑ = =+⋅⋅⋅+= K 1 2211 KK i XnXnXnXnX ii Partial molar quantities