Bubble point

At the bubble point, the following relationship holds:

${\displaystyle \sum _{i=1}^{N_{c}}y_{i}=\sum _{i=1}^{N_{c}}K_{i}x_{i}=1}$ 

where

${\displaystyle K_{i}\equiv {\frac {y_{ie}}{x_{ie}}}}$ .

K is the distribution coefficientorK factor, defined as the ratio of mole fraction in the vapor phase ${\displaystyle {\big (}y_{ie}{\big )}}$  to the mole fraction in the liquid phase ${\displaystyle {\big (}x_{ie}{\big )}}$  at equilibrium.
When Raoult's law and Dalton's law hold for the mixture, the K factor is defined as the ratio of the vapor pressure to the total pressure of the system:^[1]

${\displaystyle K_{i}={\frac {P'_{i}}{P}}}$ 

Given either of ${\displaystyle x_{i}}$ or${\displaystyle y_{i}}$  and either the temperature or pressure of a two-component system, calculations can be performed to determine the unknown information.^[4]

• Phase diagram
• Azeotrope
• Dew point