# Problem: How many grams of ethylene glycol, C 2H4(OH)2, must be added to 400.0 g of water to yield a solution that will freeze at -8.35 °C?a) 37 gb) 111 gc) 75 gd) 151 g

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94% (151 ratings)
###### FREE Expert Solution

We’re being asked to determine the mass of ethylene glycol (C2H4(OH)2) that must be added to 400.0 g water to get a solution with a freezing point of –8.35 ˚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 mass of C2H4(OH)2 needed.

94% (151 ratings) ###### Problem Details

How many grams of ethylene glycol, C 2H4(OH)2, must be added to 400.0 g of water to yield a solution that will freeze at -8.35 °C?

a) 37 g

b) 111 g

c) 75 g

d) 151 g

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.

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