Questions from class - Lecture 7 Flashcards Preview

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Which important parameter appears in the enthalpy of mixing and how does it depend on temperature?

The Flory-Huggins interaction parameter. It goes as 1/T, but will depend on the energy balance of the interactions between species A and B. When the balance is negative, the interaction parameter will increase as the temperature increases - when the balance is positive, the interaction parameter will decrease as the temperature increases.


How is the stability of a mixture evaluated on the basis of the shape of the curve describing the free energy of mixing?

When the second derivative of the free energy of mixing is greater than 0, it is stable, and when it is less than 0, it is unstable.


How is the phase diagram of a mixture derived from the energy of mixing?

Calculate free energy from many temperatures, and plot the binodal and spinodal curves from the minima and inflection points respectively.


Where is the critical point?

The critical point is the lowest point on the spinodal curve.