Question

The dipole-dipole interaction energy between rotation polar molecules is proportional to___, where 'r' is the distance between polar molecules.

• A. \(\frac{1}{r^4}\)
• B. \(\frac{1}{r^9}\)
• C. \(\frac{1}{r^3}\)
• D. \(\frac{1}{r^2}\)
• E. \(\frac{1}{r^6}\)

Answer 1

Answer: (E)

For polar molecules, the interaction energy between two dipoles is given by the formula: \[ U(r) = \frac{C}{r^6} \] where \( C \) is a constant and \( r \) is the distance between the molecules. This relationship arises due to the nature of dipole-dipole interactions, where the energy is inversely proportional to the sixth power of the distance between the dipoles.
Thus, the dipole-dipole interaction energy between rotating polar molecules is proportional to \( \frac{1}{r^6} \).

The correct option is (E) : \(\frac{1}{r^6}\)

Answer 2

The dipole-dipole interaction energy between rotating polar molecules (like in gases) is inversely proportional to the fourth power of the distance between the molecules. This behavior is due to the thermal averaging of dipole orientations as the molecules rotate. Correct Answer: \(\frac{1}{r^6}\)