Latent Heat Problem/ Phase Change .

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SUMMARY

The discussion centers on calculating the time required for an ice cube tray to freeze, starting with 12 one-gram cubes at 20°C, which cool to 12°C in 10 minutes. The user employs the formula Q=mcΔT, recognizing that it takes 1 cal/g/°C to lower the temperature from 20°C to 0°C, and must also account for the latent heat of fusion for water to ice. The key insight is to assume a constant rate of heat flow out of the ice, which is crucial for determining the freezing time.

PREREQUISITES
  • Understanding of thermodynamics, specifically latent heat and phase changes.
  • Familiarity with the formula Q=mcΔT for heat transfer calculations.
  • Knowledge of the specific heat capacity of water (1 cal/g/°C).
  • Basic principles of heat transfer and thermal equilibrium.
NEXT STEPS
  • Research the concept of latent heat of fusion for water (334 J/g).
  • Learn about heat transfer rates and their impact on phase changes.
  • Explore practical applications of Q=mcΔT in real-world scenarios.
  • Study the effects of varying temperatures on the freezing process of liquids.
USEFUL FOR

Students studying thermodynamics, educators teaching physics concepts, and anyone interested in the practical applications of heat transfer and phase changes in materials.

jdhutto
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Latent Heat Problem/ Phase Change...Please Help!

At 1:00pm you place an ice cube tray in the freezer. Each of the 12 1-gram cubes has a temperature of 20°C. At 1:10 the water temperature has dropped to 12°C. At what time will you have ice?

i have been messing around with this problem for like 20 minutes and I am missing something, I am using Q=mc delta T, and i know it takes 1 cal/g/degree C to go from 20 down to zero, and you have to add the latent heat from water to ice to that to get Q total, i just can't figure out how to work the time factor in...please help, thanks
 
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Hi jdhutto,

jdhutto said:
At 1:00pm you place an ice cube tray in the freezer. Each of the 12 1-gram cubes has a temperature of 20°C. At 1:10 the water temperature has dropped to 12°C. At what time will you have ice?

i have been messing around with this problem for like 20 minutes and I am missing something, I am using Q=mc delta T, and i know it takes 1 cal/g/degree C to go from 20 down to zero, and you have to add the latent heat from water to ice to that to get Q total, i just can't figure out how to work the time factor in...please help, thanks

I believe that they want you to assume that the rate of heat flow out of the ice is constant. Do you see what to do now?
 

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