Some corresponding-states correlations use the critical compressibility factor Zc. rather than the acentric factor (, as a third parameter. The two types of correlation (one based on Tc, Pc, and Zc, the other on Tc. Pc, and () would be equivalent were there a one- to-one correspondence between Zc and (. The data of App. B allow a test of this correspondence. Prepare a plot of Zc vs. ( to sec how well Zc correlates with (. Develop a linear correlation (Zc = ( + b() for nonpolar substances.