An aqueous solution of ethanol has a density of 1.025g/mL and concentration 2M. What is the molality of this solution?
None of these
The correct option is B2.14m Let the volume of solution be 1000 mL. Weight of solution =1.025×1000=1025 g Molarity of ethanol is 2 M i.e it contains 2 moles per 1000 mL of the solution. Mass of ethanol = 2 mol × 46 g/mol = 92 g Mass of solvent (water) = mass of solution – mass of solute (ethanol) Mass of water = 1025 g – 92 g = 933 g
Molality=Moles of solutemass of solvent (g)×1000 =2933×1000=2.14m