Example 18.2-2 Determination of Diffusivity
> restart;
> z2:=z1+17.1*cm;
> Ptot:=755*mmHg;
> T:=273.15*K;
From the ceng301 data and the function vappr, we get for the vapor
pressure of CCl4:
vappr(273.15)
ans =
5.5562 <-- 41.67mmHg?? The text gives 33 mmHg.
> vapP:=5.5562*kPa;
> mmHg:=kPa*101.325/760;xA1:=vapP/Ptot;
> pB1:=(1-xA1)*Ptot;pB2:=Ptot;
> S:=0.82*cm^2;evaprA:=.00208*cm^3/hr;
> SGCCl4:=1.595; From Felder & Rousseau, Table B.2
> rhoA:=SGCCl4*g/cm^3;
> MWA:=153.82*g/mol; From Appendix E.1 of BSL
> hr:=3600*second;NA:=evaprA*rhoA/MWA/S;
> c:=Ptot/Rgas/T;
> Rgas:=82.0578*cm^3*atm/mol/K;
> atm:=101.325*kPa;c;
> DAB:=NA*(z2-z1)/c/log(1/(1-xA1)); From eq. 18.2-14 using xA2=0.
![[Maple Math]](images/ex18221.gif)
>
The book found a higher value due to the lower vapor pressure of CCl4 at 0C.