Answer:
Molar mass of solute is 183.4g/mol
Explanation:
Using Raoult's law it is possible to find moles of solute, thus:

Where pressure of solution is 53.15 mmHg, pressure of pure solvent is 54.68 mmHg and mole fraction is:
53.15 mmHg = X 54.68 mmHg
<em>0.9720 = X</em>
<em />
Mole fraction of solvent is defined as moles of solvent / total moles.
Moles of solvent are:
286.8g × (1mol / 46.07g) = 6.225 moles of ethanol.
That is:

<em>Where Y are moles of solute.</em>
6.051 + 0.9720Y = 6.225
0.9720Y = 0.174
Y = 0.179 moles of solute
As mass of solute dissolved was 32.83g. Molar mass of solute is:
32.83g / 0.179mol = <em>183.4g/mol</em>