The matter it can be found in three states of aggregation: solid, liquid or gaseous (although a fourth state is currently known, the plasmatic state). The passage of a substance from one state to another (from solid to liquid, from liquid to gaseous, from gaseous to solid or vice versa) is produced by the increase or decrease of the temperature or pressure to which it is subjected.
These changes they do not chemically modify the qualities of matter, but rather its shape and physical characteristics. When matter is in a liquid state, the particles are at a certain distance from each other. In the gaseous state, this distance is even greater than in the other states, and matter has neither volume nor shape.
The phenomena that occur when matter goes from a liquid state to a gaseous state and vice versa are:
- Vaporization. Process by which matter goes from a liquid to a gaseous state due to an increase in temperature. For instance: when the sun’s heat turns the water in puddles into water vapor. There are two types of vaporization: boiling and evaporation.
- Condensation. Process by which a substance goes from the gaseous state to the liquid state when its temperature decreases. For instance: when water vapor condenses and forms water particles that make up clouds. This process occurs naturally (condensation is part of the water cycle) and can also be carried out in laboratories.
- Liquefaction. Process by which a gaseous substance passes to the liquid state by increasing its pressure, although the process occurs at low temperatures as well. For instance: the liquid contained within the lighters.
Evaporation and boiling
The evaporation and the boiling are types of vaporization that occur when a matter goes from a liquid to a gaseous state. Evaporation occurs when matter in a liquid state receives a certain amount of temperature and occurs only on the surface of the liquid. It also occurs gradually, that is, slowly. For instance: When the temperature rises, the water changes from a liquid state to water vapor.
Boiling only occurs at a specific temperature level for each substance. Boiling occurs when all the molecules in the liquid reach a temperature that is equal to their boiling point (the temperature at which the vapor pressure of the liquid equals the pressure surrounding the liquid). For instance: The boiling point of water is at 100ºC, that is to say, at this temperature the water turns into gas.
Examples of liquids to gases (vaporization)
- The smoke from a cup of tea or coffee is the liquid evaporating.
- The alcohol in an alcohol bottle evaporates when it is opened.
- The water in wet clothes dries up from the sun and evaporates.
- The water in a pot boils at its boiling point.
Examples of gases to liquids (condensation)
- The water vapor that clouds a mirror.
- Water vapor in the atmosphere turns into water particles that form clouds.
- The dew that forms in the morning on the leaves of plants.
- Nitrogen turns into liquid nitrogen.
- Hydrogen turns into liquid hydrogen.