Question

Calculate the freezing point and boiling point of a solution containing 8.25 gg of ethylene glycol (C2H6O2)(C2H6O2) in 92.4 mLmL of ethanol. Ethanol has a density of 0.789 g/cm3g/cm3.

Calculate the freezing point of the solution.

Calculate the boiling point of the solution.

Answer 1

These values can be calculated using the following formulae:

Where m is the molality of the solute (ethylene glycol) and k_eb is the ebulloscopic constant of ethanol (1.07 K*kg/mol)

Where k_cryo is the cryoscopic constant of ethanol (1.99 K*kg/mol). W

We need to calculate the molality of ethyleneglycol. For this, we need the number of moles:

And the number of kg of ethanol:

The molality is then:

We can then calculate:

Which is the same as an increase in 1.95 °C, since the normal boiling temperature of ethanol is 78.4°C, the boiling point of this solution will be 80.4°C.

The normal freezing point of ethanol is -114.1°C, so the freezing point of the solution is -117.7 °C.