How Do You Calculate Total Pressure in Mixed Gas Systems?

AI Thread Summary
To calculate total pressure in mixed gas systems, the first question involves combining nitrogen and oxygen in a 50L cylinder, resulting in a total pressure of 30kPa, while the user's incorrect answer was 300kPa. The second question concerns a 10L flask of nitrogen at 500mmHg connected to a 4L flask of oxygen at 800mmHg, with the final pressure after opening the tap being 586mmHg, contrary to the user's answer of 1300mmHg. The user employed the ideal gas law and partial pressure formulas but is struggling to understand the correct calculations. The discussion emphasizes the importance of accurate application of gas laws in determining pressures in mixed gas systems.
ravadongon
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Question 1: 5L of nitrogen at 100kPa and 298K and 5L of oxygen at 200kPa are pumped into a evacuated 50L cylinder. Temperature remains constant, what is the total pressure in the cylinder?

Correct Answer: 30kPa
My answer: 300 kPa

Question 2: A 10L flask containing nitrogen at 500mmHg is connected via a closed tap to a 4L flask containing oxygen at 800mmHg pressure, if the tap is opened what will be the final pressure assuming temperature remains constant?

Answer: 586mmHg
My answer: 1300mmHg

Formulas I used:

pV = nRT (to find mols)
PA = (nA/nA+nB) x PT

How did they get these answers...cos I can't seem to get them..?? Any help would be appreciated...
 
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This thread is also in the Chemistry section. It has a reply in this section so I would suggest that it continues in that section of the forums.

Please do not double post ravadongon.

The Bob (2004 ©)
 
Last edited:
The Bob said:
This thread is also in the Chemistry section. It has a reply in this section so I woul suggest that it continues in that section of the forums.

Please do not double post ravadongon.

The Bob (2004 ©)

sorry, I'll get a mod to delete it...
 
ravadongon said:
sorry, I'll get a mod to delete it...
It's alright. I am not telling you off in a way where I am going to take my leather belt off. :-p

Believe me, we all get told once, even if we did not start the thread. Just make sure you are not one of the people that have to be told more than once. :smile: :-p

So long as no one else posts here, there should be no need to get a moderator to delete it. :smile:

The Bob (2004 ©)
 

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