There are various physical processes Through which matter can change its state of aggregation, alternating between solid, liquid and gaseous according to the specific conditions of pressure and temperature to which it is subjected.
The State of aggregation A substance can change if energy is supplied or extracted from it, usually in the form of heat. Due to this, the amount of energy with which its particles vibrate varies, allows a greater or lesser proximity between them and thus alters the physical nature of the substance in question.
These processes are: fusion, solidification, freezing, evaporation, boiling, sublimation, reverse sublimation, liquefaction and condensation.
- Fusion. It is the passage from solid to liquid matter by increasing the temperature of the solid (up to its melting point).
- Solidification. It is the passage from liquid to solid matter as the pressure of the liquid increases.
- Freezing. It is the passage from liquid to solid matter as the temperature of the liquid decreases.
- Evaporation. It involves the transition from a liquid to a gaseous state by increasing the temperature of the liquid. This process occurs gradually and slowly.
- Boiling. It involves the transition from a liquid to a gaseous state by increasing the temperature of the liquid to its boiling point (temperature at which the vapor pressure of the liquid equals the pressure surrounding the liquid).
- Sublimation. It is the passage from solid to gaseous, without previously passing through the liquid state. This process occurs at a very specific temperature and pressure.
- Reverse sublimation or deposition. It is the passage from a gaseous substance to a solid without first passing through the liquid state. It occurs at very specific pressures and temperatures.
- Condensation. Converts gases into liquids by decreasing the temperature of the gases.
- Liquefaction. It is the passage from a gas to a liquid when, in addition to lowering the gas temperature, a high pressure is used.
- Melt ice. By increasing the temperature of the ice, either by leaving it at room temperature or by subjecting it to fire, the helo will lose its solidity and will become liquid water.
- Melt metals. Various metallurgical industries operate based on the melting of metals in large industrial furnaces, to be able to shape or fuse them with others (alloys).
- Melt candles. The candles, made from paraffins (a mixture of hydrocarbons, alkanes), remain solid at room temperature, but when subjected to the fire of the wick, they melt and become liquid again until they cool down again.
- Volcanic magma. Subjected to enormous pressures and temperatures, this substance that inhabits the earth’s crust can be thought of as molten or molten rock.
- Burn plastics. By increasing their temperature above ordinary conditions, certain plastics quickly become liquid, although they re-solidify just as quickly once the flame is not in direct contact with them.
- Melt cheese. Cheese is a dairy coagulate that is usually more or less solid at room temperature, but when subjected to heat it becomes a liquid until it cools down again.
- The welds. The welding process involves the fusion of a metal through a high-temperature chemical reaction, which allows it to join other metal parts as they become less solid and, upon cooling, regain their strength together.
- See more: Solids to Liquids
Examples of solidification and freezing
- Turn water into ice. If we remove heat (energy) from the water until it reaches its freezing point (0 ° C), the molecules of the liquid will lose their mobility and the liquid water will go to the solid state: ice.
- Make clay bricks. Bricks are made from a mixture of clays and other components that form a semi-liquid paste. They take their specific shape in a mold, where they are baked to remove moisture and give in return solidity and resistance.
- Igneous rock formation. This type of rock originates from the liquid volcanic magma that is part of the deep layers of the earth’s crust and when it springs to the surface, it cools, densifies and hardens until it becomes solid stone.
- Make candy. Sweets are made by burning and melting common sugar, until a brownish liquid substance is obtained. Once poured into a mold, it is allowed to cool and harden to obtain a (solid) caramel.
- Make sausages. Sausages such as chorizo or blood sausage are made from animal blood, coagulated and marinated, cured inside the skin of pig tripe.
- Make glass. This process begins with the fusion of the raw material (silica sand, calcium carbonate and limestone) at high temperatures, until it reaches the right consistency to blow and shape it. The mixture is then allowed to cool until it achieves its characteristic solidity and transparency.
- Make tools. From liquid steel (alloy of iron and carbon) or cast, various tools and utensils for everyday use are made. The liquid steel is allowed to cool and solidify in a mold and thus the tool is obtained.
Examples of evaporation and boiling
- Boil water. By bringing water to 100 ° C (its boiling point), its particles take up so much energy that it loses liquidity and becomes steam.
- Clothes hanging. After washing, we hang the clothes so that the heat of the environment evaporates the residual humidity and the fabrics remain dry.
- Coffee smoke. The smoke that emerges from a hot cup of coffee or tea is nothing more than part of the water present in the mixture that turns into a gaseous state.
- Sweating. The drops of sweat that our skin secretes evaporate into the air, thus cooling the temperature of our surface (they extract heat).
- Alcohol or ether. These substances, left at room temperature, will evaporate in a short time.
- Get sea salt. The evaporation of sea water loses the salt that was normally dissolved in it, and allows its collection for dietary or industrial uses, or even to desalinate the water (which from steam would be converted into a liquid, now free of salts).
- Hydrological cycle. The only way that the water from the environment rises to the atmosphere and can cool down to precipitate again (the water cycle), is for it to evaporate from seas, lakes and rivers, as it is heated during the day by the direct action of the sun. .
Examples of sublimation
- Dry ice. At room temperature, ice made from carbon dioxide (CO2, first compressed and then frozen) returns to its original gaseous form.
- Evaporation at the poles. Since in the Arctic and Antarctic water is not in its liquid form (they are below 0 ° C), part of it is sublimated directly into the atmosphere from its solid form of ice.
- Naphthalene. Composed of two condensed benzene rings, this solid material used as a repellent for moths and other animals transforms from solid to gas at room temperature.
- Arsenic sublimation. When brought to 615 ° C, this solid (and highly toxic) element loses its solid form and becomes a gas, without going through a liquid on the way.
- The wake of the comets. As they approach the sun, these traveling rocks gain heat and much of the CO2 frozen begins to sublimate, tracing the well-known “tail” or visible trail.
- Iodine sublimation. When heated, iodine crystals transform into a very characteristic purple gas without the need to melt first.
- Sulfur sublimation. Sulfur is usually sublimated as a way to obtain “flower of sulfur”, its presentation in the form of very fine powder.