How Many Moles of NO2 and SO2 Are in the Mixture?

AI Thread Summary
A sample containing NO2 and SO2 has a total pressure of 120 torr, with a partial pressure of NO2 at 43 torr. The ideal gas law (PV = nRT) is used to calculate the number of moles for each gas. An initial calculation yielded 3.1 x 10^-3 moles for NO2, but the correct answer is 1.9 x 10^-3 moles. The discrepancy was due to an error in manipulating the equations, which was resolved with assistance from the forum. The discussion emphasizes the importance of careful calculations and unit management in gas law problems.
RedemistiDeus
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Homework Statement


A sample containing only NO2 and SO2 has a total pressure of 120 torr. Measurements show that the partial pressure of NO2 is 43 torr. If the vessel has a volume of 800.0 ml and the temperature is 22.0°C, how many moles of each gas are present?

Homework Equations



PV = nRT

The Attempt at a Solution


I tried to solve it using the equation above by solving for n for each gas (using their given pressure).
For the n of NO2, I had the answer 3.1 x 10-3 (using n = PV/RT).
But the book provides a different answer for it which is 1.9 x 10-3.

My question is I would like to know how my answer turned to be incorrect. I don't know any other possible methods of solving this than the ideal gas law.
Thank you.
 
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I suspect you have either an arithmetic mistake and/or a mistake in units.

Please post the details of your calculations.
 
Book answer is correct.
 
Okay guys, I got it. I had an error in manipulating the equations. Thank you PF for helping me resolve the problem!
 
RedemistiDeus said:
Okay guys, I got it. I had an error in manipulating the equations. Thank you PF for helping me resolve the problem!

I'm curious as to how you arrived at the correct answer. Could you show your work?
 
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