Show that the osmotic pressure of a real solution is given by V=RT ln aA. Go on

Show that the osmotic pressure of a real solution is given by ΠV=–RT ln aA. Go on to show that, provided the concentration of the solution is low, this expression takes the form ΠV=ϕRT[B] and hence that the osmotic coefficient ϕ (which is defined in Problem 5E.2) may be determined from osmometry.

Data in Problem 5E.2

The osmotic coefficient ϕ is defined as ϕ=−(x_A/x_B) ln a_A. By writing r=x_B/x_A, and using the Gibbs–Duhem equation, show that we can calculate the activity of B from the activities of A over a composition range by using the formula

Transcribed Image Text:

In B=0-0(0)+ -S10=1¹ dr r r