Medical Dictionary
Main Entry:
Ra·oult's law Pronunciation:
rä-'ülz- Function:
noun : a law in physical chemistry: the fraction by which the vapor pressure ofa liquid is lowered when a small amount of a substance that is nonvolatile, not capable of being dissociated, and usually not a high polymer is dissolved in it is equal to the ratio of the number ofmoles of the solute to the total number of moles of all components of the solution
Raáoult /ro-ü,/ François–Marie (1830–1901), Frenchchemist. 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 nonelectrolytedissolved. 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 thesolute. This recognition led to the formulation of Raoult's law. The law made possible the determining of molecular weights of dissolved substances.
[rah-oolz] 
