Calculate density of Oxygen at STP

In summary: R values.In summary, the conversation is about calculating the density of oxygen at STP using the ideal gas law. The attempt at a solution involves using the formula PV=nRT and setting the volume to 1 m3, pressure to 1 atm, and temperature to 273 K. However, the answer obtained is significantly different from the book answer of 1.43 kg/m3. The discrepancy is most likely due to incorrect units used for the gas constant, which can be found in a table of values and should be chosen to match the units used for pressure and volume.
  • #1
EroAlchemist
10
0

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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  • #2
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.
 
  • #3
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
 
  • #4
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
 
  • #5




Your approach is correct, but it seems like you made a calculation error in the last step. The book answer of 1.43 kg/m3 is the correct answer. Here is the correct calculation:

n = (X grams Oxygen / 16g/mol Oxygen)
V = 1 m3
P = 1 atm = 101325 Pa
R = 8.315 J/mol K
T = 273 K

Using the ideal gas law, PV = nRT, we can rearrange it to solve for density (d = m/V):

d = (nRT)/V
d = (X grams Oxygen / 16g/mol Oxygen) * (8.315 J/mol K) * (273 K) / (1 m3)
d = (X/16) * (2263.295 J/m3 K)
d = (X/16) * (0.002263295 kg/m3 K)

Now, we know that at STP (Standard Temperature and Pressure), the density of oxygen is 1.43 kg/m3. So, we can set the above equation equal to 1.43 kg/m3 and solve for X:

1.43 kg/m3 = (X/16) * (0.002263295 kg/m3 K)
X = 1.43 * 16 * (1/0.002263295)
X = 10.15 grams

Therefore, the density of oxygen at STP is 10.15 grams/m3 or 1.43 kg/m3, which matches the book answer. Keep in mind that the units for density should be in kg/m3, not g/m3, so always double check your units when doing calculations.
 

Related to Calculate density of Oxygen at STP

1. What is the formula for calculating density of Oxygen at STP?

The formula for calculating density of Oxygen at STP is density = mass/volume.

2. What is the value of density of Oxygen at STP?

The value of density of Oxygen at STP is 1.429 g/L.

3. What is the unit of measurement for density of Oxygen at STP?

The unit of measurement for density of Oxygen at STP is g/L (grams per liter).

4. How do you determine the mass of Oxygen at STP?

The mass of Oxygen at STP can be determined by using the ideal gas law: PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant, and T is temperature.

5. Can the density of Oxygen at STP vary?

No, the density of Oxygen at STP (standard temperature and pressure) is a constant value. However, it can vary at different temperatures and pressures.

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