Calculate the activity coefficients in the system methanol (1) – toluene (2) from the data measured by Ocon, et al. [71] at atmospheric pressure assuming ideal vapor phase behavior. Try to fit the untypical behavior of the activity coefficients of methanol as function of composition using temperature independent g^{E}-model parameters (Wilson, NRTL, UNIQUAC).

Explain why the activity coefficients of methanol show a maximum at high toluene concentration.

The vapor pressure constants are given in Appendix A. Experimental data as well as molar volumes, r and q values can be downloaded from the textbook page on www.ddbst.com. For the calculation, ideal vapor phase behavior should be assumed.

[71] Ocon J., Tojo G., Espada L., Anal.Quim., 65, 641-648, 1969