What is the molar mass of toluene if 0.85 g of toluene depresses the freezing point of 100. g of benzene by 0.47^$\circ$C K_f of benzene is 5.12^$\circ$C/m. A) 927 g/mol B) 92.6 g/mol C) 81.8 g/mol D) 78.0 g/mol E) 10.7 g/mol

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Quizplus · Accepted Answer

The molar mass of toluene can be calculated using the formula for freezing point depression: $\Delta T_f = K_f \times m$, where $\Delta T_f$ is the change in freezing point, $K_f$ is the cryoscopic constant of the solvent (benzene in this case), and $m$ is the molality of the solution. The molality $m$ can be further expressed as $m = \frac{\text{moles of solute}}{\text{kg of solvent}}$. Rearranging the formula to solve for the molar mass ($M$) of toluene, we get $M = \frac{\text{mass of toluene}}{\text{moles of toluene}} = \frac{\text{mass of toluene} \times \text{kg of benzene}}{\Delta T_f / K_f}$. Given that $\Delta T_f = 0.47 ^\circ C$, $K_f = 5.12 ^\circ C/m$, mass of toluene = 0.85 g, and mass of benzene = 100 g = 0.1 kg, substituting these values into the formula gives a molar mass close to 92.6 g/mol.

What Is the Molar Mass of Toluene If 0 ∘\circ∘ C Kf of Benzene Is 5

What Is the Molar Mass of Toluene If 0 $\circ$ C K_f of Benzene Is 5