Which liquid has the lowest boiling point and why?
Do you have list from which to choose or are we to look through thousands of chemicals and try to pick the right one?
The liquid with the lowest boiling point among commonly encountered substances is helium. The boiling point of helium is extremely low, at around -268.93 degrees Celsius or -452.07 degrees Fahrenheit.
To determine why helium has the lowest boiling point, we need to consider the concept of boiling point. Boiling point is defined as the temperature at which the vapor pressure of a liquid equals the atmospheric pressure surrounding the liquid. When this occurs, the liquid changes to its gaseous state.
The boiling point of a substance primarily depends on the intermolecular forces present between its molecules. Intermolecular forces are the attractive forces between molecules that influence their behavior. These forces include London dispersion forces, dipole-dipole forces, and hydrogen bonding.
Helium is a noble gas, which means it exists as individual atoms rather than molecules. The helium atom is held together by weak London dispersion forces, which are the weakest intermolecular forces. These forces arise from temporary fluctuations in electron distribution, resulting in slight instantaneous dipoles.
Due to the extremely low mass of helium atoms, the London dispersion forces present are very weak. As a result, helium atoms don't require much thermal energy to overcome these forces and transition from liquid to gas. This is why helium has such a low boiling point compared to other substances.
It is worth noting that while helium has the lowest boiling point among commonly encountered substances, there are other substances with even lower boiling points. For example, liquid hydrogen and liquid nitrogen have lower boiling points than helium, but they are not as commonly encountered in daily life.