Increase gas pressure in unchanged volume

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Homework Help Overview

The discussion revolves around a problem involving gas pressure in a fixed volume scenario. The original poster outlines a situation where the pressure of a gas needs to be increased from 1 bar to 6 bar in a volume of 36 m³, while maintaining a constant temperature. The challenge is to determine the amount of gas required to achieve this pressure increase.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the implications of the ideal gas law and the relationship between pressure, volume, and temperature. There are questions about the assumptions made regarding temperature remaining constant and the effects of adding gas to a fixed volume.

Discussion Status

Some participants have pointed out the need to consider standard temperature and pressure (STP) in calculations. There is acknowledgment of the dynamic nature of the system, where changes in one variable affect the others. Guidance has been offered regarding the importance of understanding the concept of moles in relation to gas quantities.

Contextual Notes

Participants note that the original poster has not provided any calculations, which may limit the depth of the discussion. The mention of the compressor's specifications is seen as potentially extraneous to the core problem of gas behavior in a fixed volume.

wli
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Situation:
Start pressure: p1=1 bar;
Volume: V=36m3;
Temp.: T1=T.

Now I need to increase the pressure to 6 bar, but the volume remains unchanged. So:
End pressure: p2=6 bar;
Volume: V=36m3;
Temp.: T2=T.

So volume and temperature remain unchanged.

What amount of gas (m3) do I need to add to increase the pressure with 5 bar (p2-p1).

Compressor gives 185 l/s, max. working pressure is 7 bar.

I know p*V/T=p*V/T but I'm struggling to calculate the required volume.


Werner
 
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You haven't given any calculations of your own. Anyway, think of the ideal gas law in its exact form. I hope you are right about the two temps being the same.
 
wli said:
Situation:
Start pressure: p1=1 bar;
Volume: V=36m3;
Temp.: T1=T.

Now I need to increase the pressure to 6 bar, but the volume remains unchanged. So:
End pressure: p2=6 bar;
Volume: V=36m3;
Temp.: T2=T.

So volume and temperature remain unchanged.

What amount of gas (m3) do I need to add to increase the pressure with 5 bar (p2-p1).

Compressor gives 185 l/s, max. working pressure is 7 bar.

I know p*V/T=p*V/T but I'm struggling to calculate the required volume.


Werner

Try ignoring the numbers for the compressor and imagine the container only.
 
Any calculations you make will have to take into account STP or Standard Temperature and Pressure. You also have to know that to raise the pressure in a fixed volume container will also raise the temperature. But then after you have raised the pressure, and the temp went up with it, the pressure will drop as you let the compressed gas cool to the original temp. The whole thing is a dynamic system in which changing anyone factor will change the other two.

First you have to understand STP so follow this first link for a tutorial.

http://searchcio-midmarket.techtarget.com/sDefinition/0,,sid183_gci539342,00.html

Converting all calculations to STP after the fact gives you a basis to make comparisons.

Another helpful tutorial is the one on an "Ideal Gas" and you can find it at the next link

http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/idegas.html

Finally you are missing one factor in your question and that is the term "mole" which refers to the absolute quantity of gas in any fixed volume system at any temperature and pressure.

The next link is to a calculator to allow you to figure out all the info you needto know to achieve your goal.

http://www.1728.com/stp2.htm
 
Last edited:

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