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There can be VLE data for mixtures of four or more components, but such a boiling-point diagram is hard to show in either tabular or graphical form. For such multi-component mixtures, as well as binary mixtures, the vapor–liquid equilibrium data are represented in terms of K values (vapor–liquid distribution ratios) [1] [2] defined by
This may be written in the following form, known as the Ostwald–Freundlich equation: =, where is the actual vapour pressure, is the saturated vapour pressure when the surface is flat, is the liquid/vapor surface tension, is the molar volume of the liquid, is the universal gas constant, is the radius of the droplet, and is temperature.
= the vapor–liquid equilibrium concentration of component in the vapor phase = the vapor–liquid equilibrium concentration of component in the liquid phase (/) = Henry's law constant (also called the K value or vapor-liquid distribution ratio) of a component
The equilibrium constant of a chemical reaction is the value of its reaction quotient at chemical equilibrium, a state approached by a dynamic chemical system after sufficient time has elapsed at which its composition has no measurable tendency towards further change.
The Van 't Hoff equation relates the change in the equilibrium constant, K eq, of a chemical reaction to the change in temperature, T, given the standard enthalpy change, Δ r H ⊖, for the process. The subscript r {\displaystyle r} means "reaction" and the superscript ⊖ {\displaystyle \ominus } means "standard".
The definition of a w is where p is the partial water vapor pressure in equilibrium with the solution, and p* is the (partial) vapor pressure of pure water at the same temperature. An alternate definition can be a w ≡ l w x w {\displaystyle a_{w}\equiv l_{w}x_{w}} where l w is the activity coefficient of water and x w is the mole fraction of ...
Using mass and enthalpy balances in addition to vapor-liquid equilibrium data and enthalpy-concentration data, operating lines can be constructed using the Ponchon–Savarit method. [ 5 ] If the mixture can form an azeotrope , its vapor-liquid equilibrium line will cross the x = y line, preventing further separation no matter the number of ...
By adding a correction factor, known as the activity (, the activity of the i th component) to the liquid phase fraction of a liquid mixture, some of the effects of the real solution can be accounted for. The activity of a real chemical is a function of the thermodynamic state of the system, i.e. temperature and pressure.