In this experiment you will measure the stretching frequencies of different functional groups in a series of organic molecules. Then you will compute the spectra in Gaussian. The computed spectra will be calculated in the gas phase. How is that going to affect the calculations

If infrared radiation of a given frequency strikes a sample composed of molecules having a vibrational frequency the same as that of the incident radiation, the molecules absorb radiation and the energy of the molecule is increased. However, if the incident frequency differs from the characteristic frequencies of the molecule, the radiation passes through undiminished, or in some experiments, it is reflected. The vibrational frequencies for a particular molecule are determined primarily by the masses of the atoms in the molecule and the strengths of the bonds connecting them. For a diatomic molecule, this frequency can be derived from Hooke's law and is written as:

F=1/2pi*(w/k)^1/2

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)

level 4 to level 2 : ))