# Properties of solutions - Propylene Glycol

9) Calculate the mass of propylene glycol (C3H8O2) that must be added to 0.340 kg of water to reduce the vapor pressure by 2.88 torr at 40 °C.

10) Calculate the freezing point and boiling point of an antifreeze solution that is 50.0 % by mass of ethylene glycol (C2H6O2) in water.

11) Calculate the freezing point and boiling point of a barium chloride solution that is 4.0 % by mass of barium chloride in ethanol.

13) What is the osmotic pressure of a solution formed by dissolving 44.2 mg of aspirin (C9H8O4) in 0.358 L of water at 25 °C?

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#### Solution Preview

9) Calculate the mass of propylene glycol (C3H8O2) that must be added to 0.340 kg of water to reduce the vapor pressure by 2.88 torr at 40 °C.

molar mass of propylene glycol = 76

mass of water = 340 g

molar mass of water = 18

no. of moles of water, n1 = 340 / 18 = 18.89

lowering of vapor pressure can be given as

P = Xsolute P

where P = pure V.P of water = 55.3 torr

Xsolute = P / P = 2.88 / 55.3 = 0.052

Now, X solute = mole fraction of solute

Xsolute = nsolute / (nsolvent + nsolute)

After calculations,

Nsolute = 1.033

N = mass / molar mass

Therefore, mass = N X molar mass = 1.033 X 76 = 78.5 g

10) Calculate the freezing point and boiling point of an ...

#### Solution Summary

It investigates the properties of solutions, such as vapor pressure, osmotic pressure, the freezing point and boiling point.