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molality, mole fraction, and molarity

I don't know how to this problem!

please show all the work..!

 

Question: a solution containing equal masses of glycerol(C3H8O3) and water has a density of 1.10 g/mL. Calculate

a) the molality of glycerol

b)the mole fraction of glycerol

c) the molarity of glycerol in the solution

kingchemist Wed, 02/29/2012 - 03:02

So you have 1kg of glycerol per kg of water. Find molar mass of glycerol and find the number of moles glycerol in 1000 g (1kg). This is molality (moles of solute per kg of solvent)

Mole fraction - find the molar mass of water. Find moles of water in 1000g. Add moles of water to moles glycerol to get total moles. Mole fraction of glycerol = moles glycerol/total moles

Mass of solution (assuming 1kg of each) = 2kg or 2000g. From density, this will have a volume of 2000/density. Now you know volume, and you know the number of moles of glycerol in 1kg of glycerol, molarity = number of moles/volume of solution in L