Answer the following statement(s) true (T) or false (F)

Question

A. The “gamma” refers to the activity coefficient in the liquid phase, while the “phi” refers to the mixture fugacity coefficient in the vapor phase.
B. The approach is most beneficial for systems that behave as ideal solutions, such as benzene + toluene.
C. The approach has value for systems when the system pressure is high.
D. The approach is more complicated than Raoult’s Law or Modified Raoult’s Law, since the vapor-phase composition is a variable in the calculation of the mixture fugacity coefficients.
E. None of the above are false.

Answer 1

A. Incorrect. This is true. These are the definitions of the variables that are used to name the modeling technique.
B. Correct. For ideal solutions, the activity coefficient (the gamma in gamma-phi) is 1 by definition, so using a model for the activity coefficient is unnecessary for these systems.
C. Incorrect. This is true. At high pressures the ideal gas law is less likely to be accurate, so real gas models are helpful.
D. Incorrect. This is true. For Raoult’s Law and Modified Raoult’s Law, the composition of the vapor-phase can be solved directly. However, for the gamma-phi approach, the vapor-phase composition is an independent variable in the calculation of the mixture fugacity coefficient.
E. Incorrect. One statement is false.
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