- Raoult's law
- Ra·oult's law rä-'ülz- n a law in physical chemistry: the fraction by which the vapor pressure of a liquid is lowered when a small amount of a substance that is nonvolatile, not capable of being dissociated, and usu. not a high polymer is dissolved in it is equal to the ratio of the number of moles of the solute to the total number of moles of all components of the solutionRa·oult rȧ-ü François-Marie (1830-1901)French chemist. Raoult is known for developing the theory of solutions. He discovered about 1886 that the freezing point of an aqueous solution is lowered in proportion to the amount of nonelectrolyte dissolved. He recognized that the effect of the amount of solute dissolved on the solvent's freezing point was due to a change in the vapor pressure of the solvent brought about by the presence of the solute. This recognition led to the formulation of Raoult's law. The law made possible the determining of molecular weights of dissolved substances.
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the partial pressure of a volatile component of an ideal solution is equal to the mole fraction of that substance in solution times its vapor pressure in the pure state at the temperature of the solution; it is true only for ideal solutions and ideal gases.
Medical dictionary. 2011.