calculate the molality of aq glucose solution in which mole fraction of glucose is 0.05

Question

calculate the molality of aq glucose solution in which mole fraction of glucose is 0.05

Answer 1

Hi Kriti,

 

molality = (number of moles of solute/(kg of solvent)

 

The "aq" means aqueous, or water. Imagine that we have 0.05 mole of glucose solute and 0.95 mole of water, going off of the mole fractions.

 

1 mole of water = 18.015 g. So, 0.95 moles of water has a mass of (0.95)(18.015 g)(1kg / 1000 g) = 0.01711 kg.

 

molality = 0.05 moles glucose / 0.01711 kg water = 2.92 mol/kg