Average distance at STP

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In summary, to find the average distance between nitrogen molecules at STP, divide the mass density of nitrogen by the molecular mass of nitrogen to get the number of molecules per unit volume. Then cube root this value to get the molecules per length. Use the pressure in a gas equation to calculate the length, but make sure to check the units to ensure they cancel out. One person in the conversation made a mistake by using the density of lead instead of nitrogen.
  • #1
mlee
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who can help me solve this?
what's the average distance between nitrogen molecules at STP?

Thanx
 
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  • #2
Divide the mass density of nitrogen by the molecular mass of nitrogen to find the number of nitrogen molecules per unit volume. Use that to find the average distance between them.
 
  • #3
I seem to have the same problem. I know that rho lead = 1.25 kg/m^3 at STP, then i divide by 28e-3 kg/mol to get molec/volume. Then i cube root this to get molec/length = 3.5 approximately. Then using the pressure in a gas equation I get l = 4.107e-8m, but i cannot get units to cancel here to get a length. I end up with something like 1.16e-8 meteres distance between the molecules--- not sure if that's right. Thanks for the ehlp.
 
  • #4
Theelectricchild said:
I seem to have the same problem. I know that rho lead = 1.25 kg/m^3 at STP, then i divide by 28e-3 kg/mol to get molec/volume. Then i cube root this to get molec/length = 3.5 approximately. Then using the pressure in a gas equation I get l = 4.107e-8m, but i cannot get units to cancel here to get a length. I end up with something like 1.16e-8 meteres distance between the molecules--- not sure if that's right. Thanks for the ehlp.

Check your density for lead - it looks a bit light! :-)
 
  • #5
And gaseous lead at STP?
 
  • #6
ugh sorry i meant rho n2 not lead--- why did i say that :( grr.
 

1. What does STP stand for?

STP stands for Standard Temperature and Pressure. It is a set of standard conditions used for measuring and comparing physical and chemical properties of substances.

2. What is the average distance at STP?

The average distance at STP, also known as the mean free path, is the average distance that a molecule travels between collisions with other molecules in a gas at standard temperature and pressure.

3. How is the average distance at STP calculated?

The average distance at STP is calculated by dividing the mean free path by the number of molecules per unit volume. This can be represented by the formula: λ = kT/(√2πd^2N/V), where k is the Boltzmann constant, T is the temperature, d is the diameter of the molecule, N is the Avogadro's number, and V is the volume of the gas.

4. Why is the average distance at STP important for gas behavior?

The average distance at STP is important for understanding gas behavior because it affects the diffusion and collision rates of gas molecules. It also provides insight into the pressure and volume relationships of gases under standard conditions.

5. How does the average distance at STP change with different gases?

The average distance at STP varies depending on the gas. It is affected by the size and shape of the gas molecules, as well as the temperature and pressure. Generally, the average distance decreases with increasing temperature and increasing pressure.

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