Chemical Forums
Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: soaring206 on April 24, 2005, 08:22:11 PM

I'm having a lot of trouble with two of my homework problems tonight. I have been completely through my textbook and all over the internet, but I can't find what I'm looking for anywhere. I have no idea where to even begin on the following two problems, so if someone could just give me a push in the right direction (like an equation or something), I'd greatly appreciate it! :)
1. Calculate the rootmeansquare (standard deviation) displacement of the nuclei of ^{12}C^{16}O in the ground state and compare it to the equilibrium bond length of 112.832 pm. (HINT: <x>=0) Use ?=(k?/?^{2})^{1/2} and k=1903 kg/s^{2}.
2. Calculate the value of <r> for the n=2, l=1, m_{l}=0 state and the n=2, l=0, m_{l}=0 state of the hydrogen atom.
Any help at all would be appreciated...thank you so much in advance!

2. Do you know the wavefunction for that state?

Unfortunately, no...that's all the information given to me in the question.

Open your book. The wavefunctions are there.

Oh, right...sorry.
n=2. l=1, m_{l}=0
1/8(2Z^{3}/?a^{3})^{1/2}(Zr/a)e^{Zr/2a}cos?
n=2, l=0, m_{l}=0
1/8(2Z^{3}/?a^{3})^{1/2}(2Zr/a)e^{Zr/2a}
a=4??_{0}?^{2}/?e^{2}

Now just take the integral of (phi<r>phi*) and you'll be set.

Hmm...thanks Mitch. I feel dumb...can't believe I didn't realize that. Lol.
Any ideas on the first one perchance?