Error in neglecting the convection term in evaporation. (a) Rework the problem in the text in $18.2 by neglecting the term xA (NA + NB) in Eq. 18.0-1. Show that this leads to
NA2 = cDAB/z2 - z1 (xA1 - xA2) (18B.2-1)
This is a useful approximation if A is present only in very low concentrations.
(b) Obtain the result in (a) from Eq. 18.2-14 by making the appropriate approximation.
(c) What error is made in the determination of 9,, in Example 18.2-2 if the result in (a) is used?