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For a COmolecule, the constant €is approximately 0.00024eV.(This number is measured using microwave spectroscopy, that is, by measuring the microwave frequencies needed to excite the molecules into higher rotational states.) Calculate the rotational partition function for a COmolecule at room temperature (300K), first using the exact formula 6.30 and then using the approximate formula 6.31

Short Answer

Expert verified

The rotational partition function of a heterogeneous diatomic molecule

Step by step solution

01

Rotational partition function:

The equation is

Zrot=∑j=0∞(2j+1)exp-j(j+1)∈kT

Here, ∈is the rotational constant, kis the Boltzmann constant, and Tis the absolute temperature.

At higher temperatures, for kT>>∈, the rotational partition function becomes as follows:

Zrot=kT∈

Substitute 8.617×10-5eV/Kfork,300Kfor T, and 0.00024eVin the equationZrot=kT∈

Zrot=(8.617×10-5eV/K)(300K)0.00024eV=107.7

Therefore, the rotational partition function of a COmolecule is107.7

02

The rotational partition function of a heterogeneous diatomic molecule:

The equations are

Zrot=∑j=0∞(2j+1)exp-j(j+1)∈kT

Expand the above summation from j=0to j=50:

Zrot=1+3exp-2∈kT+5exp-6∈kT+7exp-12∈kT+...101exp-2550∈kT

Substitute 107.7for kT∈in the above equation.

Zrot=1+3exp-2107.7+5exp-6107.7+7exp-12107.7+...101exp-2550107.7

=108.03

Therefore, the exact value of rotational partition function of a COmolecule is108.03

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