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