Question
A solution of 50g of solute 'X' is dissolved in 150 g of 'Y' solvent boils at 357.27 K. What is the molar mass of solute? (Given K_b and boiling point pure solvent is 2.77 K kg/mol and 350.06 K respectively.)
A solution of 50g of solute 'X' is dissolved in 150 g of 'Y' solvent boils at 357.27 K. What is the molar mass of solute? (Given K_b and boiling point pure solvent is 2.77 K kg/mol and 350.06 K respectively.)
B. 128 g/mol
The elevation in boiling point is given by T_b = T_b - T_b^0. T_b = 357.27 - 350.06 = 7.21 K. The formula for elevation in boiling point is T_b = K_b W_2 1000 M_2 W_1 . Substituting the given values: 7.21 = 2.77 50 1000 M_2 150 M_2 = 2.77 50 1000 7.21 150 M_2 = 2770 21.63 128 g/mol.
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