The temperature at which a gas becomes a liquid is known as the condensation point or the boiling point, depending on the process involved. The condensation point specifically refers to the temperature at which a gas condenses into a liquid when its pressure is held constant, while the boiling point refers to the temperature at which a liquid vaporizes into a gas under normal atmospheric pressure. The condensation and boiling points vary for different substances and depend on factors like pressure.
The temperature at which a liquid becomes a solid is known as the freezing point or the solidification point. When a liquid reaches this temperature, it undergoes a phase transition and changes into a solid state. The freezing point varies depending on the substance.
When a gas condenses into a liquid, the volume decreases significantly. This reduction in volume occurs because the gas molecules come closer together and become more densely packed in the liquid state. The intermolecular forces between the particles increase, leading to a more ordered arrangement and a reduction in the average kinetic energy of the molecules. As a result, the volume of the substance decreases.
On the other hand, when a liquid undergoes solidification and becomes a solid, its volume generally decreases further. This decrease in volume occurs due to the formation of a more rigid and organized molecular structure in the solid state. The particles in the liquid slow down and arrange themselves in a tightly packed, orderly manner, resulting in a further reduction in volume.
It's important to note that the exact volume changes during phase transitions can vary for different substances and may be influenced by other factors such as pressure and impurities. Additionally, some substances exhibit unusual behavior during phase transitions, such as water, which expands slightly when it freezes, leading to a decrease in density.