{{Short description|Temperature of a liquid at first bubbles}} frame|Mole fraction vs. temperature diagram for a two-component system, showing the bubble point and dew point curves. In thermodynamics, the '''bubble point''' is the temperature (at a given pressure) where the first bubble of vapor is formed when heating a liquid consisting of two or more components.<ref name = "Unit Ops"> {{Citation | last1 = McCabe | first1 = Warren L. | last2 = Smith | first2 = Julian C. | last3 = Harriot | first3 = Peter | title = Unit Operations of Chemical Engineering | place = New York | publisher = McGraw-Hill | year = 2005 | pages = 737–738 | volume = | edition = seventh | url = | doi = | id = | isbn = 0-07-284823-5}} </ref><ref name = "Che Thermo"> {{Citation | last1 = Smith| first1 = J. M. | last2 = Van Ness| first2 = H. C. | last3 = Abbott| first3 = M. M. | title = Introduction to Chemical Engineering Thermodynamics | place = New York | publisher = McGraw-Hill | year = 2005 | pages = 342 | volume = | edition = seventh | url = | doi = | id = | isbn = 0-07-310445-0}} </ref> Given that vapor will probably have a different composition than the liquid, the bubble point (along with the dew point) at different compositions are useful data when designing distillation systems.<ref name="Perry">{{cite book|editor=Perry, R.H.|editor2=Green, D.W.|title=Perry's Chemical Engineers' Handbook|edition=7th|publisher=McGraw-hill|date=1997|isbn=0-07-049841-5}}</ref>
For a single component the bubble point and the dew point are the same and are referred to as the boiling point.
==Calculating the bubble point== At the bubble point, the following relationship holds:<br> :<math>\sum_{i=1}^{N_c} y_i = \sum_{i=1}^{N_c} K_i x_i = 1</math> <br> where<br> :<math>K_i \equiv \frac{y_{ie}}{x_{ie}}</math>. K is the ''distribution coefficient'' or ''K factor'', defined as the ratio of mole fraction in the vapor phase <math>\big(y_{ie}\big)</math> to the mole fraction in the liquid phase <math>\big(x_{ie}\big)</math> at equilibrium. <br> 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:<ref name = "Unit Ops" /><br> :<math>K_i = \frac{P'_i}{P}</math>
Given either of <math>x_i</math> or <math>y_i</math> and either the temperature or pressure of a two-component system, calculations can be performed to determine the unknown information.<ref name = "Che Thermo2"> {{Citation | last1 = Smith| first1 = J. M. | last2 = Van Ness| first2 = H. C. | last3 = Abbott| first3 = M. M. | title = Introduction to Chemical Engineering Thermodynamics | place = New York | publisher = McGraw-Hill | year = 2005 | pages = 351 | volume = | edition = seventh | url = | doi = | id = | isbn = 0-07-310445-0}} </ref>
==See also== * Phase diagram * Azeotrope * Dew point
==References== {{Reflist}}
Category:Temperature Category:Phase transitions Category:Gases