Entropy How much of the water is solid?

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Discussion Overview

The discussion revolves around the thermodynamic behavior of supercooled water at -10°C, specifically addressing how much of the water will solidify when placed in an insulated environment, and the associated entropy change during this process. The scope includes theoretical considerations of phase changes, entropy calculations, and the application of thermodynamic principles in an adiabatic context.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant notes that liquid water can remain in a supercooled state below its freezing point and questions how much will solidify when placed in an insulated thermos.
  • Another participant suggests that there is a specific equation in physics for adiabatic problems that may be relevant to the discussion.
  • A different participant proposes that the problem can be approached by equating heat lost by the water to heat gained, prompting a request for the relevant equation.
  • Further, a participant raises questions about the work done under constant volume/adiabatic conditions and suggests that the energy gained by the liquid phase is related to the formation of ice, referencing the differences in chemical potential between the phases at -10°C.
  • There is a suggestion that the change in entropy of the surroundings will be zero due to the adiabatic nature of the process, while the change in entropy of the system may be calculated by assuming equivalent changes in state.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and approaches to the problem, with no consensus on the specific method to calculate the amount of solid water formed or the entropy change. The discussion remains unresolved with multiple viewpoints presented.

Contextual Notes

Participants mention the assumption that heat capacities of solid and liquid water are independent of temperature, but there may be limitations in the assumptions made regarding the thermodynamic properties and the specific equations applicable to the scenario.

StonieJ
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Question:
Liquid water can be cooled to a temperature of -10 C and stay a liquid. As it is below its freezing point it is thermodynamically unstable and will eventually turn into solid water. If you put 100 g of supercooled water at -10 C into an insulated thermos (adiabatic) it will eventually freeze into a mixture of solid ice and liquid water at 0 C. How much of the water is solid? What is the entropy change of the universe for this process? (Assume the heat capacities of solid and liquid water are independent of temperature.)



I have to admit, I have very little clue as to where to even begin with this question. Normally, every time I ask a question, I like to have some answer or idea to let people know I at least thought about it, but I simply cannot decipher this problem. I tried working with absolute entropies of the water in solid and ice forms at 263 and 273 K, but I am getting nowhere. Any advice is appreciated.
 
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there should be an equation in physics specifically for adiabatic problems.
 
The first part is simply solved by setting heat lost = heat gained. Can you write down the equation for that ?
 
here are some questions to consider

-at constant volume/adiabatic conditions what would be the work for raising the temperature. It's simple calorimetry, except that you might want to use w, instead of q. The energy gained by the liquid phase is approportionated to form the ice. The process occurs due to differences in chemical potential of the liquid and solid phase at -10C



The change in entropy of the surroudings will be zero right, since no heat is released to the surroundings. The change in entropy of the system can be found by assuming the equivalent changes in state for an adiabatic process as that of constant temperature and constant _______?
 

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