# Average distance at STP

1. Oct 9, 2004

### mlee

who can help me solve this?
what's the average distance between nitrogen molecules at STP?

Thanx

2. Oct 9, 2004

### Tide

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. Nov 5, 2004

### Theelectricchild

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 thats right. Thanks for the ehlp.

4. Nov 5, 2004

### Tide

Check your density for lead - it looks a bit light! :-)

5. Nov 5, 2004

### HallsofIvy

Staff Emeritus
And gaseous lead at STP?

6. Nov 5, 2004

### Theelectricchild

ugh sorry i meant rho n2 not lead--- why did i say that :( grr.