Solutions

In a solvent S, a compound B is partially dissociated into C and D as given below: B 2C+2D B, C and D are non-volatile in nature. The molar mass of B is 10 times the molar mass of S. The standard boiling point and the standard enthalpy of vaporization of S are 400 K and 10R J mol-1, respectively (R is the gas constant in J K-1 mol-1). A solution of B in S with an initial concentration of B as 0.25% (mass/mass) has a boiling point of 408 K at 1 bar pressure. In this solution, the mole percent of B that has been dissociated is .

At 300 K, the ratio of the molar volume of pure B in vapour phase to its molar volume in liquid phase is .

The mole fraction of B in vapour phase which is in equilibrium with this solution is .

At 300 K, an ideal dilute solution of a macromolecule exerts osmotic pressure that is expressed in terms of the height (h) of the solution (density = 1.00 g cm-3) where h is equal to 2.00 cm. If the concentration of the dilute solution of the macromolecule is 2.00 g dm-3, the molar mass of the macromolecule is calculated to be X 104 g mol-1. The value of X is . Use: Universal gas constant (R) = 8.3 J K-1 mol-1 and acceleration due to gravity (g) = 10 m s-2

Vessel-1 contains w2 g of a non-volatile solute X dissolved in w1 g of water. Vessel-2 contains w2 g of another non-volatile solute Y dissolved in w1 g of water. Both the vessels are at the same temperature and pressure. The molar mass of X is 80% of that of Y. The van’t Hoff factor for X is 1.2 times of that of Y for their respective concentrations. The elevation of boiling point for solution in Vessel-1 is % of the solution in Vessel-2.