The law of Raul was established in the distant year of 1887one 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 the law of Raul you can find out that the increasethe boiling point or the freezing point of the diluted solution in relation to the undiluted proportional to the molar accumulation of the substance and is used to find its molecular mass.
An ideal solution is one thatall of its characteristics is suitable for the relevant requirements of the law of Raoul. 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 be easy to recognize, since we only need to take into account their original property of the component and the proportionality in which the mixing occurs in a chaotic manner.
With real solutions, such a calculationalmost impossible. 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 absorbs.
The colligative characteristics of the solution arethose that mainly have a dependence 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.
The first law of Raoul combines the pressure of concentrated vapor over the solution with its composition. The definition of this law is written as: Pi = Pio * Xi.
The propor- tional pressure of the accumulated vapor ycomponents of solutions is directly proportional to the value of its mole fractions in a given solution. In this case, the proportionality coefficient will be equal to the pressure of the concentrated vapor over the insoluble component.
Since the total total result of the mole fractionsof the whole components of the solutions is equal to 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 true only for some diluted solutions.
Reduce the freezing point carefullydiluted solutions of non-volatile matter 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.
An increase in the boiling point of somediluted 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.
