# Problem: What volume of ethanol (density = 0.7893 g/cm3) should be added to 450 mL of water in order to have a solution that freezes at -15.0°C? [For water, Kf = 1.86°C/m.]A) 371 mLB) 470 mLC) 212 mLD) 132 mLE) 167 mL

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###### FREE Expert Solution

We’re being asked to determine the volume of ethanol (C2H5OH) that must be added to 450 mL water to get a solution with a freezing point of –15.0 ˚C.

Recall that the freezing point of a solution is lower than that of the pure solvent and the change in freezing point (ΔT­f) is given by:

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)

Kf = freezing point depression constant (in ˚C/m)

Recall that the molality of a solution is given by:

For this problem, we need to do the following:

Step 1: Calculate for ΔTf.

Step 2: Determine the molality of the solution.

Step 3: Calculate the volume of C2H5OH needed.

###### Problem Details

What volume of ethanol (density = 0.7893 g/cm3) should be added to 450 mL of water in order to have a solution that freezes at -15.0°C? [For water, Kf = 1.86°C/m.]

A) 371 mL

B) 470 mL

C) 212 mL

D) 132 mL

E) 167 mL

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 Freezing Point Depression concept. If you need more Freezing Point Depression practice, you can also practice Freezing Point Depression practice problems.

What is the difficulty of this problem?

Our tutors rated the difficulty ofWhat volume of ethanol (density = 0.7893 g/cm3) should be ad...as medium difficulty.

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Our expert Chemistry tutor, Jules took 4 minutes and 52 seconds to solve this problem. You can follow their steps in the video explanation above.

What professor is this problem relevant for?

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