We explain what vapor is, its presence in the atmosphere, uses and what vapor pressure is. Also, differences between gas and steam.
What is steam?
When we talk about steam, we can refer to any subject which is found in gaseous state as a consequence of having modified its pressure and temperature conditions.
In that sense, it is a concept very similar to that of gas, but with the difference that gases tend to be gases under ordinary conditions of pressure and temperature, while steam It is always the result of the heating of an element which, at room temperature, is usually solid or liquid.
What's more, when referring to steam, We generally talk about water vapor that is, the gas that liquid water becomes when we introduce enough heat to bring it to its boiling point (100° C or 212° F), that is, when the water boils or evaporates.
When it is in that state, the water continues to be odorless and tasteless, transparent, although under certain conditions of condensation it appears as a whitish stain, more or less thick, known as mist, fog or clouds, depending on its conditions of appearance.
Water vapor is extremely abundant in the atmosphere of our planet, something essential for the continuity of the hydrological cycle, and to stabilize it climatically.
Its spontaneous production in nature is due to solar rays and geothermal heat. Furthermore, it has been produced and used in numerous industries since the 18th century, when it played an eminent role in the Industrial Revolution.
Water, when transformed into steam, increases its volume 1,700 times, which generates an increase in local pressure (vapor pressure) that can be converted into mechanical work, with the appropriate instruments. That is the principle behind the steam engine, the same one that we use today to generate electricity in many parts of the world.
See also: States of water
gaseous state
Vapor exists in the gaseous state of matter in which the particles are dispersed and present a minimum force of mutual attraction, due to the high levels of internal energy they possess.
Gases do not have a defined shape or volume of their own but rather they expand until they fill the container where they are, like all fluids. At the same time, the gases are volatile, compressible and they can become plasma, or liquids or even solids, by manipulating their temperature and the pressure at which they are found.
Gas and steam
As said before, gas and vapor are practically synonymous terms, since all vapor is gaseous. However, not all gas is a vapor since the latter necessarily comes from subjecting a liquid or metallic element to a process of evaporation or vaporization, that is, from forcing it to change its physical state to a gaseous one.
Thus, for example, water vapor is a gas obtained by boiling water, while carbon dioxide is the organic gas that we exhale when breathing, and is not a form of vapor, although it leaves our body along with abundant carbon vapor. water.
Uses of steam
Steam has enormous industrial and economic applications, such as:
- Electricity generation Steam is key in the generation of electrical energy, for which a steam turbine is used. The logic of this circuit is what allows power plants with different fuels to operate (nuclear, coal or natural gas, for example), in which water is constantly heated until it boils and the steam, as it expands, mobilizes the turbines, generating the work necessary to produce electricity. About 90% of the world's electrical energy is obtained in this way.
- Domestic uses Water vapor is used to cook, clean fabrics and even to heat buildings and homes. These different uses, in the kitchen or in the boilers of a building, in turn require a certain fuel.
- Sterilization Given the high temperatures that steam can reach, it is used in sterilization procedures for floors, laboratory equipment and other materials that require a non-toxic mechanism for cleaning germs and bacteria.
- mechanical force Just as in the case of power plants, the power of steam can be used to mobilize mechanical systems, based on their need to expand. The steam engines invented during the Industrial Revolution took advantage of this property, and used it as a source of movement, in trains, ships and even steam cars, prior to the discovery of fossil fuels.
Vapor pressure
steam pressure is the force that the vapor exerts on the liquid phase of the same material in a closed system at a given temperature.
Its value is independent of the amount of liquid and gas stored, but depends on the nature of the substance. According to the International System of Units is expressed in pascals (Pa), equivalent to one newton per square meter (Nm2).
Continue with: Physical change
References
- “Steam (state)” in Wikipedia.
- “Steam” on Wikipedia.
- “Who invented the steam engine?” at Aquae Foundation.
- “Steam” in Agrarian Bulletin.
- “Main applications for steam” in TLV A Steam Specialist Company.
- “Steam” in The Encyclopaedia Britannica.
