Ideal vapor-liquid equilibrium

7 important questions on Ideal vapor-liquid equilibrium

When can a solution be considered ideal?

- When the interactions between species are similar to the interactions within a species. Such as in Heptane/Octane solutions.
- A strongly dilutes solution. For example salt in water.

Considering a closed, ideal, system with species A and B, constant P and T, what variables contribute to the equilibrium condition of the system?

Since G = H - TS
Because all interactions: A-A=A-B=B-B, there is no change in H.
Only the entropy S remains.

Explain the variables in the Boltzman entropy:

is the Bolzman constant in
is the sum of all possible configurations of molecules in a grid.
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For a two component ideal mixture, how can the Bolzman entropy be calculated?


The sum of configurations is calculated as follows:

How can the Gibbs free energy for an ideal solution be calculated?

The Gibbs free energy of a solution is the sum of the Gibbs free energy of the separate components and the mixing entropy times T.

How is the chemical potential of one component in an ideal solution derived?

For example a two component system:

on the phase line :
Taking the partial derivative of G:

How is the chemical potential of component i in an ideal gas mixture expressed?


where y is the molar fraction of gas.

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