A solution of 1.50 g of solute dissolved in 25.0 mLof H2O

Solution 93P:

Step 1: (a)

Here, we are going to determine the molar mass of the solute  if it is a nonvolatile nonelectrolyte and the solution behaves ideally.

Given that,

Mass of the solute = 1.50 g

Volume of the solvent (H2O) = 25.0 mL

Density of the solvent = 0.997 g/mL

Therefore, the mass of the solvent = 25.0 mL

                                       = 24.925 g

                                       = 0.0249 kg

We know that,

The boiling point elevation is given by:

where m is the solution molality, Kb is the molal boiling point elevation constant,

Given that,

= 100.45°C.

= 0 oC

=0.512 oC/m

Thus,

=

        = 0.8789 mol/kg

Thus,

Molality (m) = Mass of the solute/mass of the solvent (kg)

                                 =0.02188 mol

Therefore, the molar mass of the solute =

= = 68.56 g/mol