Thermodynamics - how much heat needed to raise temperature of a lake

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SUMMARY

This discussion focuses on thermodynamic calculations involving heat transfer in various scenarios. The first problem calculates the heat required to raise the temperature of Lake Erie, yielding a result of 1.67 x 1018 J. The second problem involves the interaction between steam and ice, requiring the application of latent heat and specific heat equations. The third problem examines the cooling of water vapor and its effect on an ideal gas, emphasizing the relationship between heat transfer and work done. Participants seek clarification on the application of thermodynamic principles and equations.

PREREQUISITES
  • Understanding of thermodynamic principles, specifically heat transfer
  • Familiarity with specific heat and latent heat calculations
  • Knowledge of the ideal gas law and its applications
  • Basic algebra for solving equations related to energy and work
NEXT STEPS
  • Study the calculation of heat transfer using the formula Q=mcΔT
  • Explore latent heat concepts and their applications in phase changes
  • Learn about the ideal gas law and its implications in thermodynamic processes
  • Investigate the relationship between power, energy, and time in thermodynamic systems
USEFUL FOR

Students and professionals in physics, engineering, and environmental science who are working on thermodynamics and heat transfer problems will benefit from this discussion.

sap_54
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I am working on my thermodynamics problems and I ran into a few problems on a couple of the questions:

1.) Lake Erie contains roughly 4.00*10^11 m^3 of water. (a) How much heat is required to raise the temperature of that volume of water from 11 degrees C to 12 degrees C? (b) Approxiamtely how many years would it take to supply this amount of heat by using the full output of a 1000-MW electric power plant?

*I got part A of the problem to be 1.67*10^18 J. I got really confused on part B; however, because I couldn't figure out how to relate this problem to time...

2.) Steam at 100 degress C is added to ice at 0 degrees C. Find the amount of ice melted and the final temperature when the mass of steam is 10 g and the mass of ice is 50 g.

*My equation was: (mass of steam)(Latent heat of vaporization)+(mass of steam)(specific heat of water)(T final-T initial)=(mass of ice)(Latent heat of vaporization)+(mass of ice)(specific heat of water)(T final-T initial)

I don't think this is right, though...

3.) One mole of water vapor at a temperature of 373 K cools down to 283 K. The heat given off by the cooling liquid is absorbed by 10 mol of an ideal gas, causing it to expand at a constant temperature of 273 K. If the final colume of the ideal gas is 20 L, determine the initial volume of the ideal gas.

*I used Q=mc(T final-T initial)
Found Q to = -180.9
and change in U=0 which means that the change in W= change in Q

Even though I found Q, I don't know how to find the change in Q, but someplace in this problem I think you need to use W=nRT(V final/V initial)

Any help would be greatly appreciated!
Thanks:smile:
 
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1 b. Power = Energy / time.
 

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