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Liquefied hydrogen is achieved when hydrogen gas can transition into a liquid state. This process is important in industries and science when storing and transporting hydrogen is needed. For hydrogen gas to be liquefied, extremely low temperatures are required because the molecules need to slow down significantly.
This cooling process reduces the kinetic energy of hydrogen molecules, allowing intermolecular forces to become more effective, pulling the molecules closer together to form a liquid. These conditions often require temperatures below -253°C.
In these extreme conditions, even weak intermolecular forces, like those in hydrogen gas, can overcome the natural tendency of molecules to spread out, leading to liquefaction.

London dispersion forces, also known simply as dispersion forces, are the weakest type of intermolecular forces. Despite being weak, they are the primary forces acting between non-polar molecules like hydrogen gas (H\(_2\)).
These forces arise due to the momentary imbalance of electron distribution within a molecule, creating a temporary dipole. Although these dipoles are transient and ever-changing, they can induce similar dipoles in adjacent molecules, resulting in an attraction between them.
This attraction, albeit weak, is crucial in the context of liquefying gases like hydrogen, where enough molecules are brought close enough to transition into the liquid phase at low temperatures.

Understanding non-polar molecules is key to grasping why London dispersion forces are significant for hydrogen gas. Non-polar molecules, such as H\(_2\), occur when electrons in a molecule are shared equally between atoms. There is no permanent charge separation within these molecules.
This even electron distribution means they lack a permanent dipole – unlike water molecules which exhibit strong polarity.
As a result, the forces that typically act between polar molecules, like dipole-dipole interactions or hydrogen bonding, are not present. Instead, non-polar molecules only experience London dispersion forces, making understanding these forces essential for studying molecular interactions in non-polar substances.

Several chemistry concepts are essential for understanding the behavior of intermolecular forces, particularly as they apply to hydrogen liquefaction.
Intermolecular forces are attractions that occur between molecules, essential for determining the physical properties of compounds, including boiling and melting points. The strength of these forces varies; hydrogen bonding is strong and affects molecules like water, whereas London dispersion forces are weaker and are present in all molecules.
In liquefying hydrogen, recognizing that H\(_2\) is a non-polar molecule is vital because it dictates that only London dispersion forces are relevant. By comprehending these fundamental chemistry principles, one can better predict and explain the behaviors of various substances under different conditions.