Gas pressures with (hypothetical) filter

In summary, the filter does nothing to the gas particles, and so the pressure between the containers will remain the same.
  • #1
funkyfreshcecil
2
0
Imagine I have 2 constant-volume, constant-temperature containers. Container A has a volume of 10 L and one Container B has a volume of 5 L.

My hypothetical gases Ideal Gas A and Ideal Gas B have the same properties as each other (temperature, mass, energy, heat capacity, blah blah blah).

If I insert 3 moles of Ideal Gas A and 3 moles of Ideal Gas B into Container A and connect the two containers, I'd expect the pressure to equalize between the containers, and the final distribution of the gases to be
Container A: 2 moles Gas A, 2 moles Gas B
Container B: 1 mole Gas A, 1 mole Gas B

makes sense.

Now, I restart the experiment, but this time I've placed a magic filter (possibly controlled by a demon) that only allows Gas B to pass, and insert it the connection between the two containers.

What would the distribution of the gases be?

Obviously all of Gas A stays in Container A, thanks to the filter.

Would Gas B move to Container B until the total pressure was equal between the two containers? Or would the partial pressure of Gas B move it until the Gas B pressure was equal. Or does it have to do with the number of moles in each container. Or...?
Thanks for any insight anyone who understands ideal gas laws can give!
 
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  • #2
Doesn't this depend on the properties of this magic filter? (e.g. can it do work?)
 
  • #3
Good point.

This magic filter doesn't apply any forces to the gas any more than the container walls do -- it's a Maxwell's demon-ish type filter that simply allows the passage of one type of gas particle but not the other.

For example if the two gases have molecules of different size, and the filter has holes that allow one size particle through and not the other.

Would that count as doing work? I don't think it's adding energy to the system if that happens. It's definitely messing with the entropy though.If no work were being done by the filter, my intuition says that the two containers should still equalize in pressure. Or is it just the case that each gas equalizes in pressure, if it can?
Thanks for your quick response.
 

Related to Gas pressures with (hypothetical) filter

1. What is a gas pressure?

A gas pressure is the force exerted by a gas on the walls of its container. It is typically measured in units of pressure such as atmospheres (atm) or kilopascals (kPa).

2. How does a filter affect gas pressure?

A filter can affect gas pressure by either increasing or decreasing it, depending on the type of filter and its purpose. For example, a filter designed to remove impurities from a gas can decrease the pressure by restricting the flow of gas, while a filter used to regulate gas flow can increase the pressure by creating a narrower passage for the gas to pass through.

3. What is the ideal gas law and how does it relate to gas pressure?

The ideal gas law is a mathematical equation that describes the relationship between the pressure, volume, temperature, and number of moles of an ideal gas. It states that as the number of moles and temperature of a gas remain constant, the pressure and volume of the gas are inversely proportional. In other words, as pressure increases, volume decreases, and vice versa.

4. How do you measure gas pressure with a filter?

To measure gas pressure with a filter, you can use a pressure gauge or a manometer. A pressure gauge is a device that measures gas pressure directly, while a manometer measures the difference in height between the gas and a reference liquid in a tube, which can then be converted into pressure.

5. Can a filter change the temperature of a gas and affect its pressure?

Yes, a filter can change the temperature of a gas and consequently affect its pressure. This is because filters can restrict the flow of gas, causing it to experience changes in pressure and temperature. Additionally, some filters are designed to remove heat from the gas as it passes through, causing a decrease in temperature and potentially a change in pressure.

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