In Rast method, Camphor is used as a solvent to determine molecular weight of non-volatile solutes because

The vapour pressure of a solvent is lowered by the presence of the non-volatile solute in the solution and this lowering of vapour pressure of the solvent is governed by Raoult's law , according to which the relative lowering of vapour pressure of the solvent over a solution is equal to the mole fraction of a non-volatile solute present in the solution. Howerver, in a case of binary liquid solution, if both the components of the solution are volatile then another from of Raoult's law is used . Mathematically, this from of the Raoult's can be given as: P_("total"=P_(1)^(0)X_(1)+P_(2)^(0)X_(2) . Solution which obey Raoult's law over the entire range of concentration are known as ideal solution . two types of deviation from Raoult's law, that is, positive and negative deviations are observed. Azeotrons arise due to very large deviation from Raoult's law . (When a plot of boiling point versus composition is plotted, then the type of grapgh that cannot be obtained is

The vapour pressure of a solvent is lowered by the presence of the non-volatile solute in the solution and this lowering of vapour pressure of the solvent is governed by Raoult's law , according to which the relative lowering of vapour pressure of the solvent over a solution is equal to the mole fraction of a non-volatile solute present in the solution. Howerver, in a case of binary liquid solution, if both the components of the solution are volatile then another from of Raoult's law is used . Mathematically, this from of the Raoult's can be given as: P_("total"=P_(1)^(0)X_(1)+P_(2)^(0)X_(2) . Solution which obey Raoult's law over the entire range of concentration are known as ideal solution . two types of deviation from Raoult's law, that is, positive and negative deviations are observed. Azeotrons arise due to very large deviation from Raoult's law . (When a plot of boiling point versus composition is plotted, then the type of grapgh that cannot be obtained is Select the correct option for an ideal solution : (i) Delta_("mix")=0, DeltaV_("mix")=0 (ii) DeltaS_("mix")gt 0, DeltaV=0 (iii) DeltaH_("mix")=0, DeltaSgt0 (iv) V. Pobs gt. V. P exp.