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-   -   Dalton's Law question. (http://www.physicsforums.com/showthread.php?t=191284)

 yaho8888 Oct14-07 09:11 PM

Dalton's Law question.

1. The problem statement, all variables and given/known data

A sample was collected into a 1.25L tank at 752 mm Hg and analyzed. The analysis showed 92% CO2, 3.6% NO, 1.2% SO2, and 4.1% H2O by mass(key word mass). what is the partial pressure exerted by each gas.

attempt at a solution:
I know that you need to times the percent of gas in the tank by the pressure.
But I try this question so many times keep get me the wrong answer.
so please show step by step solution please.
I am have a quiz tomorrow so please teach me how to do this problem thanks.

 eli64 Oct14-07 10:20 PM

This might work: assume 100g total mass sample. Then 92g is CO2, 3.6 g NO etc...

Calculate the mole of each gas with the above masses 92g CO2 = > ? mol CO2

Add up all the moles to get total moles

- mole fraction (mol CO2/total moles)is proportional to partial pressure/total pressure,
- total pressure is given in the problem.

 yaho8888 Oct14-07 11:40 PM

Quote:
 Quote by eli64 (Post 1466762) This might work: assume 100g total mass sample. Then 92g is CO2, 3.6 g NO etc... Calculate the mole of each gas with the above masses 92g CO2 = > ? mol CO2 Add up all the moles to get total moles - mole fraction (mol CO2/total moles)is proportional to partial pressure/total pressure, - total pressure is given in the problem.
It dosen;t seem working!
THE ANSWER OF CO2 SHOULD BE 630MM HG

 eli64 Oct15-07 12:33 PM

are you sure the % values are correct? If you add up all the numbers I get 100.9%, this could make a difference in the partial pressures

 yaho8888 Oct15-07 06:11 PM

That's how it is on the book check thousand times!

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