The law of Raoul.

Raoul's law was established in the distant 1887 by one of the famous French physicists. He bears his name. Raoult's law is based on certain connections that reduce the vapor pressure over dilute solutions of nonelectrolytes. The comparative decrease in the pressure of the impregnated vapor is the same as the mole fraction of the diluted substance. This law the French scientist derived, studying the various solutions of liquids (non-volatile) and substances (solid).

From Raoult's law, one can know that an increase in the boiling point or a decrease in the freezing point of a dilute solution in relation to a substance that is undiluted in proportion to the molar accumulation of matter is used to find its molecular mass.

An ideal solution is one that meets all of its characteristics in accordance with the relevant requirements of Raoult's law. More approximate solutions can be considered only those that relate to nonpolar gases and liquids. That is, their constituent molecules should not change their direction in the existing electric field. Consequently, the heat of their opening will be zero. And then the properties of solutions will not be difficult to find out, since it is only necessary to take into account their original property of component and proportionality, in which mixing occurs in a chaotic manner.

With real solutions, such a calculation can not be made. Because in the formation of solutions, as a rule, heat is generated or the reverse situation occurs - the solution absorbs this heat into itself.

An exothermic process is the process in which heat production takes place, and the endothermic process is the one where it is absorbed.

The colligative characteristics of the solution are those that mainly depend on the concentration of the solution, rather than on the natural natural diluted substance. Significant colligative dimensions are the pressure, the freezing point of the solution and the very proportional vapor pressure of the solvent.

Raoul's first law combines the pressure of concentrated steam over a solution with its composition. The definition of this law is written as: Pi = Pio * Xi.

The propor- tional pressure of the accumulated vapor in the solution components is directly proportional to the value of its mole fractions in this solution. In this case, the proportionality coefficient will be equal to the pressure of the concentrated vapor over the insoluble component.

Since the total result of the mole fractions of the entire components of the solutions is 1, then for the binary solution consisting of components such as A and B, we can derive the following relation, which also coincides with the expression of the first Raoult law: (P0A-PA) / P0A = XB.

The second law of Raoul is a consequence of the first law, named after the scientist from France. This law is correct only for some diluted solutions.

The decrease in the freezing temperature of carefully diluted solutions of a non-volatile substance is directly proportional to the molar accumulation of solutions, and they do not have any dependence on the natural diluted substance: T0fr-Tfr = Tfr = Km.

The increase in the boiling point of some dilute solutions of non-volatile substances does not depend on the very nature of the diluted substance, and it is directly proportional to the molar component of the solutions: T0b-Tb = Tb = Em.

The ebullioscopic constant, that is, the coefficient E, is the difference between the immediate boiling point of the solution and the temperature of the completely undiluted solution.

The cryoscopic constant, that is, the coefficient K, is the difference between the freezing point of the solution and the temperature of a completely undiluted solution.