Solution:

This is a question based on Raoult's Law which states that the partial vapour pressure of a component in a solution is directly proportional to its mole fraction in the solution.

Formula: Delta Tb = Kb x m x i

Where,

Delta Tb = Change in boiling point

Kb = Boiling point elevation constant

m = Molality of the solution

i = Van't Hoff factor

Given:

Mass of compound (non-volatile) = 1.8gm

Mass of acetone = 25gm

Boiling point of pure acetone (Tb1) = 56.28 degree Celsius

Boiling point of solution (Tb2) = 56.86 degree Celsius

Kb for acetone = 1.72gm

Molar mass of compound = ?

Determination of Molality:

Molality (m) = moles of solute / mass of solvent (in kg)

Moles of solute = Mass of solute / Molar mass of solute

Mass of solvent = Mass of acetone - Mass of solute

Molar mass of acetone = 58.08 g/mol

Moles of acetone = Mass of acetone / Molar mass of acetone

Moles of acetone = 25 / 58.08

Moles of acetone = 0.43 mol

Moles of solute = 1.8 / Molar mass of solute

Mass of solvent = 25 - 1.8

Mass of solvent = 23.2gm = 0.0232kg

Molality (m) = (1.8 / Molar mass of solute) / 0.0232

Molality (m) = 77.59 / Molar mass of solute

Determination of Change in Boiling Point:

Delta Tb = Tb2 - Tb1

Delta Tb = 56.86 - 56.28

Delta Tb = 0.58 degree Celsius

Determination of Van't Hoff Factor:

Van't Hoff factor (i) = 1 (since the given compound is non-electrolytic)

Determination of Molar Mass:

Using the formula Delta Tb = Kb x m x i

0.58 = 1.72 x (77.59 / Molar mass of solute) x 1

Molar mass of solute = (1.72 x 77.59) / 0.58

Molar mass of solute = 229.62 g/mol

Therefore, the molar mass of the non-volatile compound is 229.62 g/mol.

Conclusion:

The molar mass of the non-volatile compound is determined to be 229.62 g/mol using the Raoult's Law equation.