- #1
mikeclinton
- 7
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Homework Statement
Calculate the molecular diameter of hydrogen, assuming the spherical shape on the basis of van der Waals coefficients.
Van der Waals Coefficients for hydrogen
a = 0.244 atm L2.mol-2
b*103 = 26.6 L.mol-1
Homework Equations
Not indicated in the problem but I would think the Van der Waals equation of state.
The Attempt at a Solution
For hydrogen:
Since the constant b is an indication of molecular volume, it could be used to estimate the radius of an atom or molecule, modeled as a sphere. This leads to the following estimate of radius:
V = b/N = (26.6 x 10-6)/6.02*1023 (I have first converted b unit to m3/mol)
V = 4πr3/3
which gives r = 0.219nm
corresponding to a molecular diameter D = 0.438nm
I would like to know if my reasoning is correct; especially the equation V = b/N
I'm also confused about the inclusion of the a constant in the problem when it isn't needed as far as I know.