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Spacing between atoms. 
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#1
Apr1709, 11:25 AM

P: 176

1. The problem statement, all variables and given/known data
Hi, I've got the following problem: Calculate the spacing between atoms of an ideal gas at a temperature of 273K and a pressure of 1atm. 2. Relevant equations Mean free path equation: ʎ = 1 / 4(pi)(n)(σ²) 3. The attempt at a solution I first used the ideal gas equation PV =nRT to get n/V and thus I got 2.67 x 10^25 particles/m^3. But I dont know how I can find the radius of the atom. Am I using the wrong equation to get the spacing between atoms? Thanks! 


#2
Apr1709, 11:42 AM

Sci Advisor
HW Helper
P: 8,953

If you consider the spacing between the centres of the atoms  you don't really need the size of the atom.
Take a look at the answer and you will see that the size of an atom (0.1nm) is tiny compared to the spacing. 


#3
Apr1709, 01:49 PM

P: 176




#4
Apr1709, 06:57 PM

PF Gold
P: 3,225

Spacing between atoms.
That's what I understand from mgb_phys. 


#5
Apr2009, 04:30 PM

P: 176

So what really is the difference between the mean free path and spacing between atoms? Thanks. 


#6
Apr2009, 04:37 PM

Sci Advisor
HW Helper
P: 8,953

A mole at stp is 22.4litres.
So you have 6 10^23 atoms/22.4litres = 2x10^19 atoms/cc Or roughly 3million atoms per cm = 3nm apart. A typical atom is roughly 0.1nm in diameter so the size of the atom doesn't really matter compared to the spacing. 


#7
Jun3011, 10:26 AM

P: 2

quest: est the atomic spacing of the iron atoms.atomic mass 55.9u,density of iron found in quest is 6.585g/cm^3. 


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