What is the relative lowering in vapour pressure of an ideal solution?
Relative lowering of vapour pressure of a solution is equal to the mole fraction of solute.
The number of solvent molecules escaping into vapour phase gets reduced and as a result the pressure exerted by the vapour phase is also reduced. This is known as relative lowering of vapour pressure.
The relative lowering of vapour pressure of a dilute aqueous solution containing non volatile solute is 0.0125.
Relative lowering of vapour pressure of an aqueous solution containing nonvolatile solute is equal to mole fraction of solute. Now, molality =0.0125×10000.9875×18=0.70.
The vapor pressure of ideal solutions is related to the mole fraction of water, as defined by Raoult's law. Raoult's law is based on the observation that the partial vapor pressure of each component in a solution is a function of its mole fraction and the vapor pressure of a pure liquid at the same temperature.
What is the relative lowering in vapour pressure of 10% aqueous solution of glucose : Q. Q. The relative lowering of vapour pressure of an aqueous solution containing a non volatile solute is 0.0125.
Raoult's law for non-volatile solute : The relative lowering of vapour pressure of dilute solution containing non-volatile solute is equal to the mole fraction of solute.
Raoult's law states that “the relative lowering of the vapour pressure of a solvent by dissolving a non-volatile electrolyte is equal to the mole fraction of the solute”.
Relative lowering of vapour pressure is a colligative property that means it depends upon the number of solute molecules present in the solution with respect to the total number of molecules present in the solution.
An ideal solution or ideal mixture is a solution in which the enthalpy of solution (ΔHsolution=0) is zero; with the closer to zero the enthalpy of solution, the more "ideal" the behavior of the solution becomes.
What is an ideal solution and a non-ideal solution?
The solution which obey Raoult's law over the entire range of concentration are known as ideal solutions. When a solution does not obey Raoults's law it is called as non-ideal solution.
Examples of ideal solutions are chlorobenzene and bromobenzene, benzene and toluene, n-butyl chloride and n-butyl bromide, methanol and ethanol etc. Examples of non-ideal solutions are sugar solution, kerosene, ethanol and acetone, chloroform and acetone etc.
Note: Relative lowering of vapor pressure depends on concentration of solute. In the question, molalities of solutes are given. So, the solute whose concentration is greater that is, urea has the highest lowering of vapor pressure.
The vapour pressure of 5% aqueous solution of a non-volatile organic substance at 373 K is 750 mm.
Raoult's law does not apply to all kinds of solutions but only ideal solutions. An ideal solution has solvent-solute interactions the same as the solvent-solvent or solute-solute interaction.
The lowering of vapour pressure is equal to the mole fraction of the solute.
Raoult's law states that the mole fraction of the solute component is directly proportional to its partial pressure. Solution that obeys Raoult's law is known as the ideal solution and the solution that doesn't obey Raoult's law is known as the non-ideal solution.
According to Raoult's law the relative lowering of vapour pressure is equal to mole fraction of solute, i.e., the ratio of number of moles of solute to total number of moles of all component in solution.
The vapour pressure is directly proportional to temperature. This means that as the temperature of a liquid or solid increases its vapour pressure also increases. Likewise, if the temperature of the liquid decreases the vapour pressure will also decrease.
On diluting the solution, its relative lowering of vapour pressure changes but molality remains constant.
What is relative lowering of vapour pressure How is it related with the molar mass of non-volatile solute?
Raoult's law for non-volatile solute : The relative lowering of vapour pressure of dilute solution containing non-volatile solute is equal to the mole fraction of solute.
Freezing point is the temperature at which vapour pressure of solution and liquid phase becomes equal. Reason: On adding non-volatile solute, vapour pressure decreases so Freezing Point also decreases depression in Freezing Point.
Relative lowering of vapour pressure of a solution is a colligative property. A colligative property of a solution depends only on the number of solute particles and not on its nature. So relative lowering of vapor pressure of a solution depends on the number of solute particles only or the mole fraction of the solute.
The relationship between the vapour pressure and boiling point is that both are inversely proportional. The more volatile liquid evaporates fast as compared to the less volatile liquid at a low temperature because the volume increases with respect to temperature so it has a low boiling point.
According to Raoults law, elevation of boiling point of a solution is directly proportional to the lowering in vapour pressure caused by the number of particles of solute present in the solution.
When NaCl is added to water a depression in freezing point is observed. This is due to lowering of vapour pressure of a solution. Lowering of vapour pressure is observed due to intermolecular interaction of solvent-solute particles.