What is the chemical potential of a diatomic gas in equilibrium?

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SUMMARY

The discussion focuses on calculating the chemical potential of a diatomic gas in equilibrium, specifically the relationship between the chemical potentials of atoms ($$\mu_A$$) and diatomic molecules ($$\mu_{A_2}$$). The correct equation relating these potentials is established as $$2\mu_{A}=\mu_{A_2}$$. The chemical potential for atoms is derived as $$\mu_A=k_BT\ln(n_A\lambda^3)$$, where $$n_A$$ is the number density of atoms and $$\lambda$$ is the thermal wavelength. The participants clarify the need to use the Gibbs condition ($$dG=0$$) to relate the chemical potentials accurately.

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Homework Statement
Consider the formation of diatomic molecules $$A_2$$ out of atoms $$A$$. Assume that the binding energy of the molecule is $$I$$, i.e., the difference in internal energy between a molecule and a pair of atoms is $$−I$$. Show that in the limit when the atoms and molecules may be regarded as classical ideal gases, except for the formation of the molecules, the equilibrium densities of the atoms and molecules satisfy $$\frac{nA_2}{n_ A^2} = √ 8λ 3 Ae I kT $$.
Relevant Equations
$$\mu_{A_2}+\mu_{A}=0$$
It is my assumption that I need to find the chemical potential of the atoms $$\mu_A$$ and for the molecules $$\mu_{A_2}$$,
then use $$\mu_{A_2}+\mu_{A}=0$$ to arrive at the given identity. For $$\mu_A$$, I found that $$\mu_A=k_BTln(n_A\lambda ^3)$$, where
$$n_a=\frac{N_a}{V}$$ and $$\lambda$$ is the thermal wavelength. My question is, how would I go about find $$\mu_{A_2}$$? I know I can find it using the partition function. But I am unsure what that would be in this case. Any advice helps. Thanks
 
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8λ3AeIkT

I suspect some sub/superscripts were needed here?
 
I don't understand your question. You have an equation relating ##\mu_A## and ##\mu_{A_2}##.

Note however that that equation is incorrect.
 
Yes, the equation should actually read $$\frac{n_{A2}}{(n_A)^2}=√8λ^3e^{\frac{I}{kT}} $$. Apologies.
 
DrClaude said:
I don't understand your question. You have an equation relating ##\mu_A## and ##\mu_{A_2}##.

Note however that that equation is incorrect.
I'm essentially trying to use the Gibb's condition ($$dG=0$$) to find how the chemical potential of the diatomic molecules relates to that of the atoms.
 
Diracobama2181 said:
I'm essentially trying to use the Gibb's condition ($$dG=0$$) to find how the chemical potential of the diatomic molecules relates to that of the atoms.

What is the stoichiometry of the reaction?
 
DrClaude said:
What is the stoichiometry of the reaction?
Two atoms create one molecule. So would the relation be $$2\mu_{A}=\mu_{A_2}$$?
 
Diracobama2181 said:
Two atoms create one molecule. So would the relation be $$2\mu_{A}=\mu_{A_2}$$?
Yes.
 

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