Thermodynamics and ice melting.

  • Thread starter Terp
  • Start date
[SOLVED] Thermodynamics and ice melting.

1. The problem statement, all variables and given/known data
An open container holds ice of mass 0.585 kg at a temperature of -13.3 *C. The mass of the container can be ignored. Heat is supplied to the container at the constant rate of 800 J/min.

The specific heat of ice to is 2100 J/Kgand the heat of fusion for ice is 334x10^3 J/Kg.

2. Relevant equations
Q=mLf where Lf = fusion for ice

3. The attempt at a solution

The first part asks:

How much time t_melts passes before the ice starts to melt?
I got the answer to this to be 20.4 minutes and I know it's correct. I used Q=cm[tex]\Delta[/tex]t= 1.63x10^4 J, where(c = 2100, m=.585, delta T = 13.3). I then used the rate of 800J/Min to get 20.4 min.

The second part asks:

From the time when the heating begins, how much time t_rise does it take before the temperature begins to rise above 0 *C?

I'm absolutely stumped. It's probably very simple and right over my head. The hint for the problem had me find how much time it'd take to melt once it got to 0*C and I found that to be 244 minutes (using Q = mLf, then Q / 800J/min to get time), which is correct.

I feel like these two are the same question, since for the first one I'm finding the time it takes for the ice to start melting, which is at 0*c. Anybody have any clue? I've tried 20.4 min and 223.6 min and Mastering Physics tells me they're both wrong. Thanks a lot!
Last edited:
The time doesn't start to rise until all the ice has melted. So you just need the sum of both times you already calculated.
So you're saying that the temperature won't start to rise over 0 until the ice has all melted? Seems like there could be other variables in play. That was the answer though, thanks a lot :). So simple it went right over my head.
Last edited:

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