Question

In order to see an absorbance peak in an ir spectrum, the molecule must ___________.

a. be symmetrical
b. have a change in dipole moment
c. only contain carbon and hydrogen
d. be asymmetric

Answer 1

The answer is b. have a change in dipole moment

When a molecule absorbs an infrared ray, its energy will increase. The energy will increase the rotational movement or the molecule. If the energy increases further, it will become the vibrational movement. Dipole moment will be increased if the vibrational movement is increased.