Question

Helium gas can be converted to the liquid form by the ________.

• A. hydrogen bonding interaction
• B. London forces of attraction
• C. dipole-induced dipole forces of attraction
• D. dipole-dipole forces of attraction

Answer 1

Answer:

B. London forces of attraction

Intermolecular Forces and Liquefaction

London Dispersion Forces

• Liquefaction of gases like Helium, which are noble gases with very weak intermolecular interactions, is primarily due to the presence of London dispersion forces.
• These forces, also known as instantaneous dipole-induced dipole forces, arise from temporary fluctuations in electron distribution within atoms or molecules.
• These fluctuations create temporary, instantaneous dipoles, which can then induce dipoles in neighboring atoms or molecules, leading to a weak, short-lived attraction between them.
• The strength of London dispersion forces increases with the size and number of electrons in an atom or molecule.

Helium Liquefaction

• Helium is the most difficult element to liquefy because its atoms have only two electrons, resulting in very weak London dispersion forces.
• For Helium to liquefy, extremely low temperatures and high pressures are required to overcome these weak attractive forces and bring the atoms close enough to interact.
• The boiling point of Helium (He) is approximately -268.9 °C (4.2 K) at standard atmospheric pressure, which is extremely low.
• Understanding these intermolecular forces is crucial in fields like cryogenics and the study of quantum fluids.