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For the vibrational motion of a diatomic molecule using a harmonic oscillator model, the allowed vibPhysical Chemistry Chemistry Question

Vibrational Frequency of a Diatomic Molecule

For the vibrational motion of a diatomic molecule using a harmonic oscillator model, the allowed vibrational energy levels can be described as

where υ is the vibrational quantum number and ν is the vibrational frequency. The vibrational frequency represented by the harmonic oscillator model is

, where k is the force constant and μ is the reduced mass.
For molecule CX, where X is an unknown atom, the vibrational absorption energy from vibrational ground state to the first vibrational excited state is 2170.0 cm-1 and the force constant is 1.903 × 103 kg s-2.

4.1.

Find the reduced mass of CX in amu.

Model Answer

To find the reduced mass of CX, μCX:

4.2.

What is atom X?

Model Answer

To find mass of the atom X, mx:

μCX = (mC + mX) = mCmX
μCX mC + μCX mX = = mCmX
mC mX – μCX mX = = μCX mC

Thus, atom X should be oxygen.

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