Final answer:
To determine the molar mass of the solute, the boiling point elevation formula is used, along with the given temperature change and the ebullioscopic constant for CCl4. After solving, none of the provided answer choices match the calculated molar mass, implying there might be an issue with the provided information or choices.
Step-by-step explanation:
To calculate the molar mass of the solute, we can use the colligative property of boiling point elevation. The formula for boiling point elevation is:
ΔT = i × Kb × m
where:
- ΔT is the change in boiling point,
- i is the van't Hoff factor (for a nonelectrolyte, this is 1),
- Kb is the ebullioscopic constant of the solvent (for CCl4, this is 5.03 °C·kg/mol), and
- m is the molality of the solution.
The molality is calculated using the mass of solute and the mass of solvent:
m = moles of solute / kg of solvent
The moles of solute can then be calculated as:
moles of solute = ΔT / (i × Kb )
For the given problem, the ΔT (0.357 °C) is known, and i=1 for a nonelectrolyte:
moles of solute = 0.357 / (1 × 5.03) ~ 0.071 moles
Finally, the molar mass (M) is:
M = mass of solute / moles of solite
M = 0.250 g / 0.071 moles ~ 3.521 g/mol
However, none of the provided answers (A: 35 g/mol, B: 50 g/mol, C: 100 g/mol, D: 200 g/mol) match this result. Therefore, please check the provided ebullioscopic constant of the solvent (Kb) and the calculations were based on the correct constants. There might have been a mix-up in the question details or answer choices.