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Homework Help: Cooling a cup of tea with ice.

  1. Sep 6, 2011 #1
    1. The problem statement, all variables and given/known data
    your 200 gram cup of tea is boiling hot. About how much ice should you add to bring it down to 65C? Ice is initially at -15C. The specific heat capacity of ice id .5cal/gC

    3. The attempt at a solution
    So the ice we add needs to absorb 7000 calories of heat.
    Heat capacity is Q/T heat divided by change in temperature . And specific heat capacity is is heat capacity divided by mass.
    So to heat the ice to 0 Celsius we have
    15C(.5cal)/gC(x) + 65(x) + 80 cal/g(x) =7000 calories.
    cleaning it up
    (15)(.5)x+65x+80x=7000 in units of energy
    the 80 comes from the latent heat for melting ice which is 80cal/gram
    and x is the unknown mass of ice.
    and i get that x=45.9 grams of ice.
     
  2. jcsd
  3. Sep 6, 2011 #2

    ehild

    User Avatar
    Homework Helper

    It looks correct.

    ehild
     
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