#### Fugacities of Mixtures: Screencasts

Explains why fugacity is important for mixtures and explains how it is used.

We suggest you list the important points in this screencast as a way to increase retention.

Describes how the fugacities of each component in a binary mixture liquid change as the temperature increases until all the liquid vaporizes.

We suggest you list the important points in this screencast as a way to increase retention.

##### Important Equations:

Fugacity of component $$i$$, $$\hat{f_i}$$, in an ideal solution:

$\hat{f_i} \; = x_iP^{sat} _i$

where $$x_i$$ is liquid mole fraction of component $$i$$
$$P^{sat} _i$$ is the saturation pressure of component $$i$$

Fugacity of component $$i$$ in a non-ideal liquid solution:

$\hat{f_i} = x_i\gamma _i P^{sat} _i$

where $$\gamma _i$$ is the activity coefficient of component $$i$$.

Fugacity of component $$i$$ in a liquid solution at elevated pressure (Poynting correction):

$\hat{f_i} = x_i\gamma _i \phi ^{sat} _i P^{sat} _i exp \left( \frac{V^L(P-P^{sat} _i)}{RT} \right)$

where $$V^L$$ is the molar volume of the liquid
$$\phi ^{sat} _i$$ is the fugacity coefficient at saturation pressure for pure component $$i$$
$$R$$ is the ideal gas constant
$$T$$ is the absolute temperature

Antoine equation for component $$i$$:

$log-{10}(P^{sat} _i) = A_i – \frac{B_i}{C_i + T}$

where $$P^{sat} _i$$ is the saturation pressure
$$T$$ is the temperature (most often in °C)
$$A_i, B_i,$$ and $$C_i$$ are constants for a given component $$i$$

Vapor-liquid phase equilibrium for component $$i$$:

$\hat{\,f^V _i} = \hat{\,f^L _i}$

where $$\hat{\,f^V _i}$$ is the fugacity of component $$i$$ in the vapor phase
$$\hat{\,f^L _i}$$ is the fugacity of component $$i$$ in the liquid phase