Find the Oxygen Mass in a Welding Tank

AI Thread Summary
To find the initial mass of oxygen in the welding tank, the ideal gas law (PV=nRT) is applied, where the gauge pressure must be converted to absolute pressure. The initial calculation yielded an incorrect mass of 0.29225 kg due to using gauge pressure instead of absolute pressure. After clarification, it was noted that gauge pressure does not account for atmospheric pressure, which is essential for accurate calculations. The discussion emphasizes the importance of understanding pressure types in gas law applications. Accurate calculations are critical for determining both the initial mass of oxygen and the mass that has leaked out.
dereklin
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Homework Statement


A welder using a tank of volume 7.40×10−2m3 fills it with oxygen (with a molar mass of 32.0g/mol ) at a gauge pressure of 3.20×105Pa and temperature of 38.7∘C. The tank has a small leak, and in time some of the oxygen leaks out. On a day when the temperature is 22.9∘C, the gauge pressure of the oxygen in the tank is 1.60×105Pa .

Homework Equations


(a)Find the initial mass of oxygen.
(b)Find the mass of oxygen that has leaked out.

The Attempt at a Solution


(a)PV=nRT
n=PV/RT
m=n*32
link to calculations
answer I got: 0.29225 kg
this answer was incorrect
 
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Welcome to PF.
Type in your calculation, please.
You used the gauge pressure instead of the pressure of the gas. Do you know what gauge pressure is?
 
ok I see where I did wrong
Thanks for the help.
 

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