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

  1. Nov 30, 2010 #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.
  2. jcsd
  3. Dec 1, 2010 #2


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    Re: Chemistry?

    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.
  4. Dec 1, 2010 #3


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    Re: Chemistry?

    I guess it is just about cryoscopic constant. What is cryoscopic constant for water? What molality of ethanol do you need?
  5. Dec 1, 2010 #4
    Re: Chemistry?

    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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