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1. In class today, two students prepared a 0.290 M solution by dissolving 49.63

ID: 706948 • Letter: 1

Question

1. In class today, two students prepared a 0.290 M solution by dissolving 49.63 g of sucrose (MW - 342.3 g/mol) in distilled water and diluting to the mark with distilled water using 500.0 mL volumetric flask. Another student measured the density of the solution and found it to be 1.030g/ml. Based on the information provided, calculate the molality of this solution. 2. In class today, two students prepared a 0.350 m solution by dissolving 47.92 g of sucrose (MW 342.3 g/mol) in 400.0 g of distilled water. Another student measured the density of the solution and found the density to be 1.037 g/ml. Based on the information provided, calculate the molarity of this solution.

Explanation / Answer

Ans 1 :

Density = mass / volume

volume of solution = 500 mL = 0.500 L

putting all the values :

1.030 = m / 0.500

m = 0.515 kg

or 515 grams

Mass of solvent = mass of solution - mass of solute

= 515 - 49.63

= 465.37 g

or 0.46537 kg

number of moles of sucrose = 49.63 / 342.3 = 0.145 moles

Molality = number of moles of solute / mass of solvent in kg

= 0.145 / 0.46537

= 0.312 m