Answer to Question #131288 in Chemistry for Joshua

Question

Calculate the molality of a solution made by dissolving 0.055Kg of dextrose in 700 grams of water?

Answer 1

Mass of dextrose = Mass of glucose = 0.055 kg = 55 g

Solution:

Dextrose is the name of a simple sugar chemically identical to glucose (C₆H₁₂O₆).

Since the molar mass of glucose is 180 g/mol (6*12 + 12*1 + 6*16 = 180 g/mol)

the mole value of glucose is 0.306 moles (55 g / 180 g/mol = 0.3055 moles = 0.306 moles).

The mass of water is 700 grams which is converted to 0.7 kg.

Molality = moles of solute / kg of solvent.

Molality = 0.306 moles / 0.7 kg = 0.437 mol/kg = 0.437 molal

Answer: 0.437 mol/kg is the molality of a solution.