Indicate whether the following physical characteristics of a 1 H-NMR or IR spect
ID: 712358 • Letter: I
Question
Indicate whether the following physical characteristics of a 1H-NMR or IR spectrum are increasing or decreasing in the direction of the arrow shown below. Place you answer in each of the textboxes provided.Partial positive charge on a proton’s respective carbon in 1H-NMR?
Degree of deshielding of a proton in 1H-NMR?
Wavelength needed to affect a bond in IR?
Energy of IR needed to affect a bond in IR spectroscopy?
Explanation / Answer
ans deshielding increases
Deshielding:
If the electron density around a nucleus decreases, the proton experiences high external magnetic field, and therefore, the chemical shift shifts downfield (higher ppms) .
ans wavelength will decrease
The wave number is inversely proportional to the wavelength .
ans energy will increase
The wave number is directly proportional to Energy
ans shielding decreases
Shielding:
If there is high electron density around the nucleus, the proton experiences lower external magnetic field, and therefore, the chemical shift shifts upfield (lower ppms) .