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37.8g of water to give a freezing point of -.15 degrees C

by trixie23
Tags: 378g, degrees, freezing, point, water
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trixie23
#1
Nov30-10, 09:39 PM
P: 1
Hey, I really need help in my chem homework. :(

how many grams of ethyl alcohol CH2OHCH2OH must be added to 37.8g of water to give a freezing point of -.15 degrees C.
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symbolipoint
#2
Dec1-10, 01:58 AM
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One must either find this information in a handbook or conduct a determination experimentally. I may suspect that doing the determination experimentally could be difficult, since freezing of a liquid is being watched for. Anybody have a guess, would the solution turn turbid near or at the freezing point? One would want to gently agitate the solution during cooling to uniformly distribute the temperatures.
Borek
#3
Dec1-10, 03:03 AM
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I guess it is just about cryoscopic constant. What is cryoscopic constant for water? What molality of ethanol do you need?

sjb-2812
#4
Dec1-10, 03:19 AM
P: 427
37.8g of water to give a freezing point of -.15 degrees C

Once you have the molality, check you don't mean ethane-1,2-diol, (ethylene glycol), rather than ethanol - the two have different molecular weights, and so will generate different masses...


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