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Homework Help: Need help with mercury vs. water problem

  1. Jun 8, 2005 #1
    I need help with a problem I have struggled with for several days.
    Here is the problem:
    The specific heat of mercury is .03 cal/g degrees C, and it's boiling point is
    357 degrees C. The specific heat of water is 1 cal/g degrees C. It takes
    65 calories of energy to vaporize one gram of mercury and 540 calories to
    vaporize 1 gram of water. If both substances begin a room temperature
    (about 22 degrees C), Does it take more energy to boil a gram of mercury or
    a gram of water?
    I found where the boiling point of water is 100 degrees C...but there is so
    much information here that I cannot determine what is needed or not, and
    what order to process the information....can anyone advise?
  2. jcsd
  3. Jun 8, 2005 #2
    You need to use [itex]Q = mc(T_{f} - T_{i})[/tex] for both the water and the mercury. [itex]T_{f}, T_{i}[/itex] are the final and initial temperatures (which you are given for both water and mercury), c is the specific heat capacity and m is the mass (if you use J K^-1 kg^-1 and kg for those quantities, you'll get an answer in J).
  4. Jun 8, 2005 #3


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    You also need the latent heat of vaporization given for each sustance. The question is asking the heat needed to raise the temperature of the liquid and to vaporize it.
  5. Jun 8, 2005 #4
    Ahh ok, yeah.
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