🤓 Based on our data, we think this question is relevant for Professor Brack's class at HOFSTRA.

** Change in freezing point (ΔT_{f})** is given by:

$\overline{){{\mathbf{\Delta T}}}_{{\mathbf{f}}}{\mathbf{=}}{{\mathbf{T}}}_{\mathbf{f}\mathbf{,}\mathbf{}\mathbf{pure}\mathbf{}\mathbf{solvent}}{\mathbf{-}}{{\mathbf{T}}}_{\mathbf{f}\mathbf{,}\mathbf{}\mathbf{solution}}}$

The ** change in freezing point** is also related to the molality of the solution:

$\overline{){{\mathbf{\Delta T}}}_{{\mathbf{f}}}{\mathbf{=}}{{\mathbf{imK}}}_{{\mathbf{f}}}}$

where:

**i** = van’t Hoff factor

**m** = molality of the solution (in m or mol/kg)

**K _{f}** = freezing point depression constant (in ˚C/m)

Recall that the ** molality of a solution** is given by:

$\overline{){\mathbf{molality}}{\mathbf{=}}\frac{\mathbf{moles}\mathbf{}\mathbf{solute}}{\mathbf{kg}\mathbf{}\mathbf{solvent}}}$

**Step 1:**

ΔT_{f} = **3.66˚C** i = **1** *(benzene is a non-electrolyte)*

**m = ??** K_{f} = **1.86 ˚C • kg/mol** *(can be found in textbooks or online)*

Solving for **molality**:

${\mathbf{\Delta T}}_{\mathbf{f}}\mathbf{=}{\mathbf{imK}}_{\mathbf{f}}$

$\mathbf{3}\mathbf{.}\mathbf{66}\mathbf{\xb0}\mathbf{C}\mathbf{=}\left(\mathbf{1}\right)\left(\mathbf{m}\right)\left(\mathbf{5}\mathbf{.}\mathbf{12}\mathbf{}\frac{\mathbf{\xb0}\mathbf{C}}{\mathbf{m}}\right)$

$\mathbf{m}\mathbf{=}\frac{\mathbf{3}\mathbf{.}\mathbf{66}\mathbf{}\overline{)\mathbf{\xb0}\mathbf{C}}}{\left(\mathbf{5}\mathbf{.}\mathbf{12}\mathbf{}{\displaystyle \frac{\overline{)\mathbf{\xb0}\mathbf{C}}}{\mathbf{m}}}\right)}$** = 0.7148 mol compound**_{ }/ kg benzene

**Step 3:**

A sample of an organic compound (a nonelectrolyte) weighing 1.35 g lowered the freezing point of 10.0 g of benzene by 3.66 °C. Calculate the molar mass of the compound.

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the The Colligative Properties concept. You can view video lessons to learn The Colligative Properties. Or if you need more The Colligative Properties practice, you can also practice The Colligative Properties practice problems.

What professor is this problem relevant for?

Based on our data, we think this problem is relevant for Professor Brack's class at HOFSTRA.

What textbook is this problem found in?

Our data indicates that this problem or a close variation was asked in Chemistry - OpenStax 2015th Edition. You can also practice Chemistry - OpenStax 2015th Edition practice problems.