LearnChemE

#### Mixing and Solution: Screencast

Illustrates the changes in state variables (V, H, U, S, G) when ideal solutions form.

We suggest that after watching this screencast, you list the important points as a way to increase retention.

Describes how to use a diagram of enthalpy versus weight percent for a binary mixture to determine the final temperature when mixing is adiabatic.

We suggest that after watching this screencast, you list the important points as a way to increase retention.

##### Important Equations:

For an ideal solution

$H = x_AH_A + x_BH_B$

where $$H$$ = enthalpy (kJ/mol) of the binary solution,

$$x_A$$ and $$x_B$$  are mole fractions of the two components,

$$H_A$$ and $$H_B$$  are the molar enthalpies (kJ/mol) of the pure components at the same temperature of the solution.

A non-ideal solution can be represented as

$H = x_AH_A + x_BH_B + \alpha x_Ax_B$

where $$\alpha$$ is a non-ideal parameter.

$\Delta H_{mix} = H – x_AH_A + x_BH_B$

where $$\Delta H_{mix}$$ = heat of mixing at constant temperature.

For dissolving a solute in a solvent

$\Delta H_{mix} = H_{solution} – H_{solute} – H_{solvent}$

$x_i \gamma _i P_i ^{sat} = y_iP$

where $$x_i$$ = liquid-phase mole fraction of component $$i$$

$$\gamma _i$$ = activity coefficient of component $$i$$

$$P_i ^{sat}$$ = saturation pressure of component $$i$$

$$y_i$$ = vapor-phase mole fraction of component $$i$$

$$P$$ = pressure.