Substances tend to take one or another state of aggregation. Many substances are in the form of gases or liquids. Moreover, they have characteristic properties inherent in the corresponding state of aggregation.
Mostly gases - covalent compounds (the exception is the group of noble gases) or simple substances. Compressibility and expandability are characteristic properties of gases. Gases have weak bonds between the particles that make up them. Gas particles have high mobility, free chaotic movement that occurs in the intervals between their collisions, in which they sharply change the nature of the movement.
Liquid - the state of aggregation of substances. Its main property is the ability to unlimited change in shape, which is transformed due to the impact of mechanical tangential movements, even if their force is negligible. At the same time, the liquid practically retains its original volume. Covalent (water), as well as ionic compounds (nitric acid) and metals (mercury) can be in a liquid state.
Gases do not have their own shape and volume. They, placed in a vessel, expand and are evenly distributed over it until they occupy the entire volume. The volume of the vessel containing the gas determines its volume. The gas is capable of exerting constant pressure on the walls of the vessels, which is the same in all directions. The gases can be mixed with one another in any proportion.
Liquids, like gases, are not endowed with specific forms. They, having established themselves under the influence of gravity at a certain level, take the form of a vessel into which they are poured. But unlike gases, any liquid has a certain volume. Their compressibility is negligible. Liquids only noticeably shrink when exposed to extremely high pressures. In addition, they boil, vaporize and condense.
- Gases do not have a fixed volume, but liquids do. They are incapable of forming free surfaces. Gases tend to occupy the entire volume that is available to them.
- Fluids are extremely difficult to compress because there is very little free space between their molecules.
- Fluids form surface tension, free surfaces.