Evaporation requires the removal of heat?

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    Evaporation Heat
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Discussion Overview

The discussion centers around the concept of evaporation and its relationship with heat transfer, particularly in the context of cooling towers. Participants explore the mechanisms of evaporation, the role of latent heat, and the temperature dynamics involved in the process.

Discussion Character

  • Conceptual clarification
  • Technical explanation
  • Exploratory

Main Points Raised

  • One participant questions the idea that evaporation removes heat, suggesting that heat must be added for evaporation to occur, as seen in boiling water.
  • Another participant clarifies that while heat is needed for evaporation, it does not increase the water's temperature; instead, it is used to free water molecules, which is referred to as latent heat.
  • A third participant explains that boiling water allows for quicker evaporation due to higher temperatures, but notes that evaporation can still occur at room temperature because some water molecules possess enough energy to escape the liquid state.
  • This participant also relates the concept to personal experiences, such as sweating, where the evaporation of hotter molecules results in cooling.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between heat and evaporation, with some emphasizing the necessity of heat for evaporation and others focusing on the cooling effect resulting from the process. The discussion remains unresolved regarding the initial question posed by the first participant.

Contextual Notes

There are assumptions regarding the definitions of heat, temperature, and evaporation that remain unexamined. The discussion does not address the specific conditions under which evaporation occurs or the quantitative aspects of heat transfer involved.

dynamicproject
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I'm missing out on something here.

I'm studying how the cooling tower works and it says that the "water evaporates and removes heat". The thing is, shouldn't the heat be added to the water for it to evaporate and thus increasing the heat? If we want water to evaporate, we boil it with fire, which is once again heat addition.

Care to clarify this for me?
 
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Water needs heat to evaporate, but the heat does not increase temperature of water: the heat is used to free the water molecules. It is called the latent heat. Water gets this latent heat from the sorrounding material, so the sorroundings get cooler.
 
We boil it so that the water is hotter than the air and then it evaporates quickly. If we don't boil it then it will be room temperature, and it will still evaporate. This is because water has many molecules in it and some are more energetic than others. The "hotter" (more energetic) molecules and bits of water have enough momentum to escape the liquid and go into the atmosphere. This leaves the liquid cooler because the hot molecules have escaped. This should jive with your personal experience. If we boil water it cools down as it evaporates, the hot water is leaving. If you sweat you cool down because the hot water molecules on your body leave and what is left are colder molecules.
 
Thanks to both of you but the answer I was looking for was answered by mpv_plate. Appreciated!
 

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