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Raoult's law (/ ˈ r ɑː uː l z / law) is a relation of physical chemistry, with implications in thermodynamics.Proposed by French chemist François-Marie Raoult in 1887, [1] [2] it states that the partial pressure of each component of an ideal mixture of liquids is equal to the vapor pressure of the pure component (liquid or solid) multiplied by its mole fraction in the mixture.
[1] [2] 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. [3] For a single component the bubble point and the dew point are the same and are referred to as the boiling point.
Köhler theory combines the Kelvin effect, which describes the change in vapor pressure due to a curved surface, with Raoult's Law, which relates the vapor pressure to the solute concentration. [1] [2] [3] It was initially published in 1936 by Hilding Köhler, Professor of Meteorology in the Uppsala University.
x 1 + x 2 = 1. In multi-component mixtures in general with n components, this becomes: x 1 + x 2 + ⋯ + x n = 1 Boiling-point diagram. The preceding equilibrium equations are typically applied for each phase (liquid or vapor) individually, but the result can be plotted in a single diagram.
[2]: 264, 269–270 In a dilute solution with two components, the component with the larger molar fraction (the solvent) may still obey Raoult's law even if the other component (the solute) has different properties. That is because its molecules experience essentially the same environment that they do in the absence of the solute.
The International System of Units (SI) recognizes pressure as a derived unit with the dimension of force per area and designates the pascal (Pa) as its standard unit. [1] One pascal is one newton per square meter (N·m −2 or kg·m −1 ·s −2). Experimental measurement of vapor pressure is a simple procedure for common pressures between 1 ...
These are analogous to Boyle's law and Charles's law for gases. Similarly, the combined ideal gas law , P V = n R T {\displaystyle PV=nRT} , has as an analogue for ideal solutions Π V = n R T i {\displaystyle \Pi V=nRTi} , where Π {\displaystyle \Pi } is osmotic pressure; V is the volume; n is the number of moles of solute; R is the molar gas ...
In thermodynamics, an activity coefficient is a factor used to account for deviation of a mixture of chemical substances from ideal behaviour. [1] In an ideal mixture, the microscopic interactions between each pair of chemical species are the same (or macroscopically equivalent, the enthalpy change of solution and volume variation in mixing is zero) and, as a result, properties of the mixtures ...