Entropy Change of Universe: 6kg Block & Lake

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SUMMARY

The discussion focuses on calculating the total entropy change of the universe when a 6 kg block with a heat capacity of 300 J/K/kg at 150°C is placed in a lake at 0°C. The entropy change of the block is determined to be -788 J/K. The participants emphasize that while the heat transfer is equal, the entropy changes are not necessarily equal due to the differing temperatures of the block and the lake. The challenge lies in calculating the entropy change of the lake, which requires knowledge of its mass.

PREREQUISITES
  • Understanding of thermodynamics principles, specifically entropy.
  • Familiarity with heat transfer concepts.
  • Knowledge of specific heat capacity calculations.
  • Ability to apply the second law of thermodynamics.
NEXT STEPS
  • Calculate the entropy change of the lake using its specific heat capacity and temperature change.
  • Review the second law of thermodynamics to understand entropy in closed systems.
  • Explore heat transfer equations relevant to phase changes and temperature differences.
  • Study examples of entropy calculations in thermodynamic processes.
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Students studying thermodynamics, physics enthusiasts, and anyone involved in energy transfer calculations in thermal systems.

swain1
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Homework Statement


Calculate the changes in total entropy of the universe as a result of the following processes:
(a) A block of mass 6kg and heat capacity of 300 J/K/kg at 150oC is placed in a lake at 0oC.

Homework Equations


The Attempt at a Solution


I think I have found the entropy change of the block as -788 J/K. I am not sure how to find the entropy change of the lake though as I don't know the mass.
Thanks for any help.
 
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The change should be equal but opposite. Heat is leaving the block and going into the water... What leave the block must enter the water...
 
yes the energy transfer will be the same but not the entropy.??
 

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