Why Is There Partial Pressure If All Molecules Occupy the Same Volume in a Gas?

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Partial pressure arises because each type of gas molecule contributes to the overall pressure based on its proportion in the mixture. Even though all gas molecules occupy the same volume, they exert pressure independently, meaning that if a gas mixture contains 20% oxygen, oxygen contributes only 20% of the total pressure. This concept aligns with Dalton's Law of Partial Pressures, which states that the total pressure of a gas mixture is the sum of the partial pressures of its individual gases. Ideal gas behavior assumes that molecules do not interfere with one another, which is closely observed in real-world gases. Understanding partial pressure is crucial for applications in chemistry and physics.
crays
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Hi guys, I'm just wondering why is there partial pressure when they said all molecule occupy the same volume in a gas. like in rtp you get 22.4 .
 
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crays said:
Hi guys, I'm just wondering why is there partial pressure when they said all molecule occupy the same volume in a gas. like in rtp you get 22.4 .

Hi crays! :smile:

Pressure (which is force per area) is basically the force caused by molecules hitting a (usually imaginary) square metre surface …

so if only 20% of the molecules are oxygen, then the oxygen is supplying only 20% of that force. :wink:

Also, as http://en.wikipedia.org/wiki/Partial_pressure#Dalton.27s_law_of_partial_pressures" says …
… ideal gas molecules are so far apart that they don't interfere with each other at all. Actual real-world gases come very close to this ideal.
 
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Thanks a lot :)
 
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