Calculate density of Oxygen at STP

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Homework Help Overview

The discussion revolves around calculating the density of oxygen gas at standard temperature and pressure (STP) using the ideal gas law. The original poster attempts to apply the formula PV=nRT but expresses confusion regarding their calculations and the expected result.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the application of the ideal gas law, questioning the units used for pressure and the molar mass of oxygen. There are suggestions to verify the conversion of pressure from atm to pascal and to reconsider the molar mass used in calculations.

Discussion Status

The discussion is ongoing, with participants providing guidance on unit conversion and raising questions about the original poster's calculations. There is no explicit consensus yet, as multiple interpretations of the problem are being explored.

Contextual Notes

Participants note the importance of using consistent units for pressure and volume and highlight the need to clarify the molar mass of oxygen gas, which is relevant to the calculations being attempted.

EroAlchemist
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Homework Statement


Calculate the density of Oxygen at STP using the ideal gas law


Homework Equations



PV=nRT

The Attempt at a Solution



n = (X grams Oxygen / 16g/mol Oxygen)
I set V = to 1 m3
P = 1 atm
R = 8.315 J/Mol K
T = 273 K

PV = nRT
PV/RT = n
1/(8.315*273) = X grams Oxygen / 16g/mol Oxygen
[1/(8.315*273)]*16 = X grams Oxygen
X = .007g/m3

Book answer is 1.43 kg/m3. I'm way off somewhere.
Thanks for any help!
 
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The SI unit of pressure is the pascal. 1 atm = 101,325 Pa. Try this in the equation and see what you get.
However I'm not sure about the *16 you got, you might want to look that up it doesn't seem right, but I can't remember how you work it out.
 
EroAlchemist said:
n = (X grams Oxygen / 16g/mol Oxygen)

Oxygen gas consist of O2molecules. The atomic weight of the oxygen atom is 16 g/mol. The molar weight of the oxygen gas is 32 g/mol.

ehild
 
As madmike already signaled - watch your units. There are plenty of possible R values to select for to fit units used for volume and pressure, the one you used requires you to use pressure in Pa.

Check out table in http://en.wikipedia.org/wiki/Ideal_gas_constant
 

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