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Homework Help: OMG this problem is making me mad please help

  1. Nov 4, 2007 #1
    OMG this problem is making me mad please help!!!

    1. The problem statement, all variables and given/known data
    How much heat is required to convert 2.50 kg of solid ice from a temperature of -11.5°C to liquid water at a temperature of 60.0 °C? (The specific heat of ice is cice = 0.50 kcal/kg°C and the heat of fusion for water is Lf = 79.7 kcal/kg.)


    2. Relevant equations



    3. The attempt at a solution
    M = 2.5kg
    Steps: -11.5 deg C to 0 deg C
    Heat fusion at 0 deg C
    0 deg C to 60 deg C

    I converted bother specific heats to Jewels by multiplying by 1000 and 4.19
    0.5 = 2095
    79.7 - 333943

    Q1 = M*Ci*CH T = 2.5 * 2095 * (0+11.5) = 60231.25J
    Q2 = MLf = 2.5 * 333943 = 834857.5J
    Q3 = M*Cw*CH T = 2.5 * 4190 * (60-0) = 10475J

    Q1 + Q2 + Q3 = 9.06E^5 j
     
    Last edited: Nov 4, 2007
  2. jcsd
  3. Nov 4, 2007 #2
    nevermind I got it...I had to use 4186.8 instead of 4190!!
     
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