The phase diagram given below shows the relationship between vapor pressure and temperature for pure ethanol and for a solution of ethanol containing a nonvolatile solute.

Use this diagram to determine the approximate molality of the solute in solution. (K_b for ethanol is 1.2 °C/m)

The boiling point of a solution composed of 1.21 g caffeine in 60.0 g ethanol is elevated by 0.127°C. Determine the molar mass of caffeine.

Magnesium chloride is dissolved in 150.0 mL of water to make a 12.5% MgCl₂ solution by mass. The solution has a density of 1.105 g/cm³. Calculate the mass of solute or solvent that must be added in order to make the boiling point of the solution 108.2°C. The van't Hoff factor of MgCl₂ is 2.70.

38.2 g Na₂SO₄ (molar mass = 142.04 g/mol) is dissolved in 1470 g of water (Kb = 0.512 ^oC/m). What is the boiling point of the solution?