Temperature at which ground state and first excited state have equal populations

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Homework Help Overview

The discussion revolves around determining the temperature at which the ground state and first excited state of hydrogen gas have equal populations. The original poster presents a scenario involving the Boltzmann distribution and the energy difference between the two states.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to apply the Boltzmann equation to find the ratio of populations and questions whether equal populations imply a ratio of one. Participants discuss the implications of assuming equal populations in the context of the formula.

Discussion Status

Participants are engaged in clarifying the assumptions needed to solve for the temperature at which the populations are equal. There is recognition of the original poster's method, but some confusion remains regarding the interpretation of the population ratio.

Contextual Notes

The original poster expresses uncertainty about whether to assume the population ratio is one when both populations are equal, indicating a potential misunderstanding of the relationship between temperature and population ratios in this context.

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Homework Statement


Consider a pure hydrogen hydrogen gas ata tempeature of 10080 K. What is the ratio of the populations of the ground state(n=1) to the first excited state(n=2). Note that the energy difference is 1.634e-18 joules between these two states. At what temperature would both levels have equal populations?


Homework Equations



Boltzmann equation: N(B)/N(A)= g(b)/g(a) exp[(E(A)-E(B))/kT
g=2*n^2

The Attempt at a Solution


finding N(B)/N(A) was easy. N(2)/N(1)=2(2)^2/2(1)^2*exp(1.634e-18 joules)/(10080 K)(1.380 *10^-23))= .000031665

I had a difficult time finding the Temperature when both populations are equal. When both populations are equal, does that imply N(a)/N(b) = 1 because N(a)=N(B)?

Now finding the temperature is simple : 1=4 exp(1.634e-18 joules/(T(1.380e-23)) => T= -85411.7 Kelvins.

The only problem is I don't know if I should assume N(B)/N(A) = 1 , just because the temperatures are equal
 
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No, you shouldn't assume N(B)/N(A) = 1 because the temperatures are equal.
You should assume it because you assume that the populations are equal; then you fill in the formula and solve for the temperature where this occurs.

So you have obtained the right answer with the right method but with a wrong way of thought :smile:
 
CompuChip said:
No, you shouldn't assume N(B)/N(A) = 1 because the temperatures are equal.
You should assume it because you assume that the populations are equal; then you fill in the formula and solve for the temperature where this occurs.

So you have obtained the right answer with the right method but with a wrong way of thought :smile:

sorry, I meant to say that the populations are equal, so should I assume that N(a)/N(b)=1 since N(a)=N(b)
 
Then you got the right answer by the right method and a typo :)
 

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