Calculating Oxygen Mass and Leak in a Tank Using Ideal Gas Law

[tweety24]

Homework Statement

A welder fills a tank, volume 7.60 x 10^-2 m^3, with oxgyen (32.0 g/mol) at gauge pressure 3.25 x 10^5 Pa and temp. 36.0 degrees C. The tank has a small leak, and some of the oxygen leaks. When temp. is 22.4 degrees C, pressure of oxygen in tank is 1.80 x 10^5 Pa.

Find initial mass of oxygen.
Find mass of oxygen that leaked out.

Homework Equations

pV = nRT

The Attempt at a Solution

I understand that I need to find the answer to the first part in order to get the answer to the second part. I used the ideal gas law equation to solve the first part and got the answer to be 308 grams but it keeps telling me that's wrong.

 

[rock.freak667]

Try converting the gauge pressure to absolute pressure by adding the atmospheric pressure to the gauge pressure.

 

[tweety24]

thanks I tried that and got the correct answer :)