[CHM 331] Textbook Problem & Your Problem

[Andrew J. Pounds]

On 11/10/13 07:10, Aaron L Featherston wrote:
>
> Dr. Pounds,
>
>
> For Problem 22, I am able to find the fundamental vibrational 
> frequencies for D2 and HD. However, I am having difficulty in solving 
> for the spectroscopic dissociation energy for D2 and HD using table 
> 13.4. I do not see a clear relationship between Do for H2 and the 
> others in order to solve for Do.
>
>

You have to compute the fundamental vibrational frequency using the new 
reduced masses for HD and D2.  I see that equation later in your e-mail. 
   Now, since the force constant (the curvature of the potential well) 
is determined by the electronic environment, it is not dependent on the 
masses.  Therefore the same force constant used for H2 can be used for 
HD and D2.  In other words the potential well is not changing when you 
change isotopes -- but the locations of the energy levels inside the 
well is changing.  If the bottom of the well is the same for all the 
species, then you should be able to compute the locations of Do using 
your new fundamental vibrational frequencies for D2 and HD.


> For problem 54, do we have to use equation 13.82 or can we follow 
> example 13.7 and solve for the equilibrium dissociation energy in a 
> similar manner.
>

Since example 13.7 fundamentally assumes that you are using using 
equation 13.82 the answer is yes.


> Lastly, in problem 56, to solve for the force constant, do we follow 
> problem 22, and use Ve=(1/2Pi)sqrt(K/u), where Ve is the fundamental 
> vibrational frequency in table 13.4, and solve for k?
>

That will work...

>
> Thank you for your help.
>
>
> Sincerely,
>
>     Aaron Featherston
>
>

-- 
Andrew J. Pounds, Ph.D.  (pounds_aj at mercer.edu)
Professor of Chemistry and Computer Science
Mercer University,  Macon, GA 31207   (478) 301-5627
http://faculty.mercer.edu/pounds_aj

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