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Homework Help: Find the mass and side length of unknown ice cube?

  1. Jan 25, 2016 #1
    1. The problem statement, all variables and given/known data
    transfer 650 EJ (10^18 joules) into an ice cube of unknown size. the temperature of h20 increases from -10c to 20c.

    1) q=mc(t2-t1)
    2) for phase change q=m(F)

    specific heat of ice (c)= 2.22x10^3 J.kg^-1.K-1
    heat of fusion (f)= 3.33x10^5 J/kg
    specific heat of water (c) = 4186 J.kg^-1.K^-1)
    2. Relevant equations
    what is the side length and mass of cube?

    3. The attempt at a solution
    First I would use eqn 1 for the heating of ice from (-10C to 0C): q=650EJ, c t= 10C and solve for mass?
    then use second equation for phase change solid to liquid (0C) using q=650,f and also solve for mass?
    use eqn 1 again and solve for m of water going from (0C to 20C) q=650EJ, c, t=20c

    Then I would sum the masses and solve for volume?
  2. jcsd
  3. Jan 25, 2016 #2


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    It's good that you see to break the problem up into 3 parts. However, in your solution you have assumed that 650 EJ are added for each part. But, 650 EJ is the total amount of heat added for the entire process of going from -10 C to 20 C.
  4. Jan 25, 2016 #3
    I am not given any mass information so I cannot find Q of each step. any way to combine the equations? like Q= (m)(c)(t) + (m)(f)
  5. Jan 25, 2016 #4
    How much heat does it take to start out with 1 kg of ice at -10 C and end up with liquid water at 20 C?
  6. Jan 25, 2016 #5
    Thank you for the responses, I appreciate it!! so I figure out how much energy it takes for 1kg of ice to go from -10c to 20c and then I can use that relationship to figure out mass with 650EJ?
  7. Jan 25, 2016 #6
  8. Jan 25, 2016 #7


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