How Do You Calculate the Mass of Oxygen in a Cylinder Using the Ideal Gas Law?

[physgrl]

Homework Statement

A fixed mass of oxygen (O2, molecular mass = 32 g/mol) is contained in a cylinder whose volume is 2.80 liters. The pressure is 148 atm when the temperature is 23oC. Find the mass of oxygen in the cylinder.

a. 20 g
b. 80 g
c. 140 g
d. 280 g
e. 546 g

Homework Equations

PV=nRT
m=n*molar mass

The Attempt at a Solution

148atm*2.80L=n*8.314*296.15
n=0.17 moles

m=n*molar mass
m=0.17*32
m=5.5g

and that is not a possible answer :s

 

[technician]

Units again!

 

[physgrl]

hehe thanks :s
is the pressure supposed to be in Pa then??

 

[technician]

Has to be!

 

[Liquidxlax]

It's good to remeber that nearly everythig in thermodynamics has to be in energies which are in joules which are N*m

 

[physgrl]

thank you! :)

 

[physgrl]

is the only wrong unit the pressure one??
because now i am getting 558g

 

[technician]

you should have volume in m^3