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An aqueous solution of 2 percent non-volatile solute exerts a pressure of 1.004 bar at the boiling point of the solvent. What is the molecular mass of the solute? |
51.3 g mol-1 61.3 g mol-1 41.3 g mol-1 71.3 g mol-1 |
41.3 g mol-1 |
An aqueous solution of 2 percent non-volatile solute means 2 g of solute is present in 100 g of solution. Weight of solvent = 100 - 2 = 98 g \(\frac{P^o - P}{P^o}\) = \(\frac{W_B}{M_B}\) x \(\frac{M_A}{W_A}\) \(\frac{1.013 - 1.004}{1.013}\) = \(\frac{2}{M_B}\) x \(\frac{18}{98}\) MB = 41.3 g mol-1 |