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

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SUMMARY

The discussion clarifies the concept of partial pressure in gases, emphasizing that even though all gas molecules occupy the same volume, their contribution to pressure varies based on their proportion in the mixture. According to Dalton's Law of Partial Pressures, each gas exerts pressure independently, and the total pressure is the sum of the partial pressures of each gas. For instance, if oxygen constitutes 20% of the gas mixture, it contributes 20% to the overall pressure. This principle holds true under ideal gas conditions, where molecules do not interfere with one another.

PREREQUISITES
  • Understanding of Dalton's Law of Partial Pressures
  • Basic knowledge of gas laws and behavior
  • Familiarity with ideal gas concepts
  • Knowledge of pressure measurement units
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  • Explore the Ideal Gas Law and its applications
  • Investigate real gas behavior and deviations from ideality
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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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