Pressurization in an enclosed space

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Discussion Overview

The discussion revolves around the behavior of water in an enclosed, indestructible container when heated to the point of vaporization, exploring concepts of pressure, phase changes, and the implications of supercritical fluids. The scope includes theoretical considerations and conceptual clarifications regarding gas laws and phase diagrams.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether the Ideal Gas Law applies when water is boiled in a confined space, suggesting that the gas produced from a liquid may not conform to standard gas behavior.
  • Another participant points out that the water would not boil but instead reach a critical point, becoming a supercritical fluid, which is neither gas nor liquid.
  • It is noted that the 22.4 L/mol volume for gases is only applicable under standard temperature and pressure, which would not be the case in this scenario.
  • A participant expresses interest in calculating the pressure acting on the container due to heating and asks how this would change if the properties of the water were altered, such as through electrolysis.

Areas of Agreement / Disagreement

Participants express differing views on the behavior of water under these conditions, particularly regarding the applicability of the Ideal Gas Law and the state of water at high temperatures. The discussion remains unresolved with multiple competing perspectives on the implications of pressure and phase changes.

Contextual Notes

Limitations include assumptions about the container's properties, the behavior of water at high temperatures, and the effects of changing the internal properties of the water. The discussion does not resolve the complexities of phase transitions or the calculations of pressure in this specific scenario.

Daimou43
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I have a question regarding the calculation of pressure. Not quite homework but just curious on how things work.


If I had an enclosed 18 mL (1 mol H2O) container that is indestructible/incompressible filled with water, and boil it so that all the water turns into water vapour, I get 22.4 L of gas, or would the pressure force the gas to remain in liquid form in some way or another, or would I get some combination of the two?

I'd also assume there'd be a large amount of pressure acting on the container as well due to expansion and whatnot.


I'm not so sure the Ideal gas law applies in such a situation, as the gas is produced from a liquid and the other values don't quite apply... (as temperature increases, the pressure increases linearly?)


Am I looking for a case of thermal expansion rather than gaseous expansion, or do both apply? I'm also unsure what else is relevant for this situation.


Thanks in advance!
 
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Read up on phases and phase diagrams.

http://www.chemguide.co.uk/physical/phaseeqia/phasediags.html"
 
Last edited by a moderator:
The water would not boil. It would reach critical point at about 374 °C where it becomes a supercritical fluid, neither gas nor liquid.
 
The 22.4L/mol thing is only applicable to standard temperature and pressure. You have neither.

And yes, if the container does not give, the liquid will become supercritical.
 
Thanks for the prompt replies.

However, it seems that the premise of my question is faulty.

I'm more interested in how much pressure would be acting upon the container due to the heating... How would that be calculated?

Also, how would the behaviour change if say, instead of just increasing the temperature, I changed the internal properties of the water itself, such as converting that container into an electrolytic cell and performing electrolysis (somehow)?
 

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