Water bath and water vapor + air mixture in a closed system

In summary, there was a discussion about a vacuum chamber with a water bath at the bottom and an air and water vapor mixture filling the rest of the chamber. The system was at room temperature and in equilibrium. It was noted that the relative humidity should be 100% in this scenario, and the amount of air in the chamber does not affect the amount of water vapor. It was also discussed that the air pressure may play a role, but it was confirmed that it does not. The speaker expressed feeling like they may be missing something.
  • #1
MacIntoShiba
7
1
Hello,

At my work I came up with the following question:

Say we have a vacuum chamber. Inside the vacuum chamber we have at the bottom a water bath. The rest of the chamber is filled with a air and water vapor mixture. The whole system is placed in a room, is at room temperature and is in equilibrium.

Since the system is in equilibrium the relative humidity should be 100% (is this correct?). Therefore the partial water vapor pressure should be the same as the water vapor pressure at room temperature (for example given by the Buck equation). This water vapor pressure is only a function of the temperature.

Does this mean that the amount of air (raising the pressure in the vacuum chamber) has no effect on the amount of water vapor inside the vacuum chamber?

Does this mean that if at the start the air has 0% relative humidity (the whole system is still at room temperature) in which case the air pressure is pair will increase to pair + pvapor when the system in back in equilibrium?

I feel like I am missing something.
 
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  • #2
Yes to all your questions.
 
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  • #3
Its a bit counter intuitive, I would expect the air pressure to play a role here. Thank you for your reply.
 
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1. What is a water bath in a closed system?

A water bath in a closed system is a container filled with water that is used to maintain a constant temperature for the substances inside the closed system. It acts as a heat source or sink, depending on the temperature of the substances in the system.

2. How does the water vapor and air mixture affect the closed system?

The water vapor and air mixture in a closed system can affect the pressure and temperature inside the system. The presence of water vapor can increase the pressure, while the air mixture can affect the temperature and composition of the substances inside the system.

3. Why is a water bath used in a closed system?

A water bath is used in a closed system to maintain a constant temperature for the substances inside. This is important for experiments or processes that require precise and consistent temperature control.

4. How is the water bath temperature controlled in a closed system?

The water bath temperature in a closed system can be controlled through various methods such as using a heating or cooling element, adjusting the water level, or adding ice or salt to the water. The method used will depend on the specific needs of the experiment or process.

5. Can the water bath and water vapor + air mixture in a closed system be used for any type of experiment?

The use of a water bath and water vapor + air mixture in a closed system is commonly used in chemistry and biology experiments, but it can also be used in other fields such as engineering and environmental science. It is important to consider the specific needs and conditions of the experiment before using this setup.

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