CHEM C 343 SPECTROSCOPY EXAM FULLY SOLVED -20.

CHEM C 343 SPECTROSCOPY EXAM FULLY SOLVED #20
The reason chemist prefers to use wavenumbers is that......... - correct answer They are
directly proportional to energy to avoid confusion.

The only bonds that can absorbs IR radiation are...... - correct answer The bonds that
have a dipole moment

Strong dipoles give rise to strong absorption - correct answer which leads to larger
peaks

How do we test over the absorbance over the entire IR range? - correct answer 1)
Fourier transfer IR:most commonly used today, analyzes absorption of all wavelengths
of IR at once giving a complex readout called an interferogram
2) Monochromatic IR:that produces and detects absorbance at each individual
wavelength systematically, is an older and more intensive method

Asymmetric stretching occurs.......... Than symmetric - correct answer Higher energy

Stretching occurs at............... Than bending - correct answer higher energy

N-H stretch - correct answer 3300-3500

O-H stretch - correct answer 3500-3200

C-H stretch alkane - correct answer 3000-2850

C-H stretch alkenes - correct answer 3000-3100

C=O stretch - correct answer 1760-1665

C=C stretch - correct answer 1680-1640

Aromatic ring - correct answer 1600-1450

C-O stretch - correct answer 1260-1050

The magnetic moment of the lower energy +1/2 - correct answer is aligned with the
external field

The magnetic moment of the higher energy -1/2 - correct answer is opposed to the
external field

The frequency of absorbed energy is - correct answer directly proportional to the
strength of the magnetic field surrounding the nucleus