Solvent Goodness
A positive B indicates a good solvent, i.e. a solvent
that gives rise to an exothermic enthalpy of mixing.
This arises when c < 1/2.
When B = 0 the solvent is nearly ideal. This is important
for use of osmotic pressure to measure molar mass.
A negative B indicates a poor solvent (c > 1/2). The
enthalpy of mixing is positive here.
The goodness of solvent can be adjusted by changing