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Association Parameter Wilke Chang. It is one of the most widely used empirical expressions as a derivitive of the Stokes-Einstein equation and is used only for very dilute solution. X the association number for water x 2. In the WilkeChang relationship 332 x is the association parameter of the solvent M is the molecular mass of the solvent in u T is the temperature in K η is the dynamic viscosity in cP or mPas and V is the molar volume of analyte at boiling point under standard conditions in cm 3 mol 1 to give the diffusion coefficient in cm 2 s. WILKE and PIN CHANG University of California Berkeley California The diffusion coefficient is nor- mally defined and assumed in this study to be the proportionality constant in the rate equation writ- ten for undirectional mass trans- fer as follows.
The correlation for diffusion in water and also in nonassociated solvents may be expressed by the general equation The association parameter x is in- troduced to define the effective molecular weight of the solvent with respect t o the diffusion proc- ess. The value of the Association parameter for ether that used in Wilke-Chang Correlation is equal to Select one. The values of D m calculated by the Wilke-Chang equation using the α value for ACN were compared with those measured by the peak parking method and the Aris-Taylor method in aqueous solutions of ACN. M the molar mass of the solvent in gram mol 1 M 18 gram mol 1 for water. In addition a revised association parameter in the WilkeChang equation for water of 226 instead of 26 is likewise recommended. Wilke-Chang conversion The original equation from the Wilke-Chang5 paper reads.
International Centre for Heat and Mass Transfer Digital Library Begell House Journals Annual Review of Heat Transfer.
Then the α value was correlated with the solubility parameter δ and ET of the solvents. For nonassociated solvents z 1and for water x 26. M the molar mass of the solvent in gram mol 1 M 18 gram mol 1 for water. Where an association parameter for the solvent water 226 Reid et al 1977 the molar volume of oxygen 256 cm 3 g -. In addition a revised association parameter in the WilkeChang equation for water of 226 instead of 26 is likewise recommended. Then the α value was correlated with the solubility parameter δ and ET of the solvents.