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Heat and Conservation of Energy

  1. Sep 18, 2012 #1
    1. The problem statement, all variables and given/known data

    A large punch bowl holds 3.00 kg of lemonade (which is essentially just water) at 1.00 degree celsius. A 0.055 kg ice cube at 0 degrees is placed in the lemonade. What is the final temperature of the system?

    2. Relevant equations
    Q=mcΔT
    Q=mL


    3. The attempt at a solution
    Having a hard time understanding the concept of heat lost and gained and when to use the latent heat equation in problems.
    All I really know of how to start this out is Q(water) + Q(ice)=0
     
  2. jcsd
  3. Sep 29, 2012 #2

    Borek

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    Staff: Mentor

    Lemonade cools down, ice melts. Question is, is there enough ice to cool the lemonade to zero?
     
  4. Sep 29, 2012 #3
    i have no clue tbh
     
  5. Sep 29, 2012 #4

    Borek

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    Staff: Mentor

    I was trying to point you in the right direction, you took my comment too literally. Whether there is enough ice is a thing that has to be calculated.

    How much heat is needed to melt the ice?

    How much heat would you get from the water cooling it down to 0°C?
     
  6. Sep 29, 2012 #5
    ok so for this i need to use (mass of ice)(latent heat of fusion)and (mass of water)(latent heat of fusion) ?

    i think this is somewhat on the right track. thank you sir for helping
     
  7. Sep 29, 2012 #6

    Borek

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    Staff: Mentor

    Melting the ice is a process described by the latent heat equation.

    Cooling down the water is a process described by the other equation, the one with ΔT.
     
  8. Sep 29, 2012 #7
    ah right thanks. don't know why i thought of using the latent heat equation for the water. it's just cooling down, not changing phase
     
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