The atmosphere of our planet is a unique gas mixture containing nitrogen, oxygen, carbon dioxide and some other components. It is called air. This mixture has many properties. All the most important physico-chemical and biological processes taking place around us in animate and inanimate nature are completely dependent on the composition of the air and are dependent on it. These include respiration and burning, photosynthesis and the reaction of the cycle of chemical elements in nature. This article will be devoted to the study of the physical and chemical properties of the gas composition of the atmosphere.
We will also consider in which industries, medicine and agriculture its physical characteristics can be used. For example, those that are most significant: specific gravity, density, elasticity and thermal conductivity. The article will also provide information on how to use air in modern technical instruments and devices created taking into account its physical characteristics.
How to find out the composition of the air
The gaseous mixture we breathe has long been treated by various philosophical schools as a unique substance that gives life. The Indians called it Prana, the Chinese - Qi.
In the mid-18th century, the brilliant French natural scientist A. Lavoisier, using his chemical experiments, debunked the erroneous scientific hypothesis about the existence of a special substance - phlogiston. It allegedly contained particles of unknown energy, giving life to everything that exists on Earth. Lavoisier proved that the composition and properties of air are determined by the presence of two main gases: oxygen and nitrogen. They account for more than 98%. The remainder includes carbon dioxide, hydrogen, inert elements and industrial impurities, such as gaseous oxides of nitrogen or sulfur. Studying the properties of the components of the atmosphere served as an incentive for a person to use this gaseous mixture in various branches of technology and in everyday life.
Air and its role in the life of living organisms
One of the first answers to the question of how a person uses the properties of air will be the following: we need it for breathing. Having fallen into the upper respiratory tract during inspiration, his portion reaches the lungs. In the capillaries of the alveoli, oxygen diffuses into the blood. It supplies O 2 molecules to the intercellular fluid. Blood directly contacts cell membranes that pass oxygen directly into the cytoplasm. Having received O 2 particles, the cell spends them in metabolic reactions. Unlike animals and humans, plants use elements of the atmosphere not only for respiration, but also for photosynthetic processes, extracting carbon dioxide from it.
Composition and properties of air
An example illustrating the ability of atmospheric elements to absorb thermal energy, more simply, to heat, will be as follows: if the vent pipe of a preheated flask with a ground stopper is lowered into a container with cold water, air bubbles will come out of the tube. The heated mixture of nitrogen and oxygen expands, no longer fit in the tank. Part of the air is released and enters the water. When the flask is cooled, the volume of gas in it decreases and contracts, and water flows up the flask through the vent pipe.
Consider another experiment conducted in nature studies for students in grade 2. The properties of air, for example, elasticity and pressure, are clearly visible if the inflated balloon is squeezed with your palms, and then carefully pierced with a needle. Sharp cotton and scattered rags show children gas pressure. It can also be explained to students that a person used these properties in the manufacture of pneumatic devices, for example, jack hammers, pumps for pumping bicycle chambers, and pneumatic weapons.
Physical characteristics of air
The transparency, lack of color and smell of the gaseous atmosphere that surrounds us are well known to students of the 2nd grade from their own life experience. The properties of air, for example, its lightness and mobility, can be explained to the guys on the example of wind farms. They are built on hills and hills. After all, the speed of air movement depends on the height. Such power plants are safe to operate and do not harm the environment.
Like other substances, the components of the atmosphere have mass. To solve problems in the course of inorganic chemistry, it is generally accepted that the relative molecular mass of air is 29. Given this value, we can find out which gases are lighter than the atmosphere.
These include, for example, helium, hydrogen. To create an aircraft, a person conducted experiments and studied the properties of air. The experiments were successful, and the world's first balloon flight was carried out by the French inventors, the Montgolfier brothers, already in the 18th century. The shell of their balloon was filled with a hot mixture of hydrogen, nitrogen and oxygen.
Airships - more maneuverable and better controlled devices, rise up because their shells are filled with light gases, namely helium or hydrogen. A person uses the ability of a gas mixture to compress in devices such as air brakes. They are equipped with buses, metro trains, trolleybuses. The above examples are a clear illustration of how a person uses the properties of air.
How do sound sensations arise?
One of the most important analyzers of our body is auditory. He perceives vibrations called sound waves as external stimuli. They press on the eardrum, causing vibrations in it that are transmitted to the auditory ossicles of the middle ear. A portion of the air is constantly located in the cavity of the Eustachian tube and equalizes the pressure on the eardrum. This prevents its deformation and rupture, ensuring the transmission of sound vibrations to the inner ear, where excitation occurs. According to the auditory nerves, it enters the temporal lobe of the cerebral cortex, which causes the occurrence of auditory sensations. Similar examples show us how a person uses the properties of air to carry out normal functioning of his own body.
Air in the service of man
Various characteristics of an atmospheric gas mixture: density, specific gravity, thermal conductivity, ability to compress and move, are widely used in our industry, medicine and in everyday life. The artificial respiration apparatus supplies the mixture enriched with oxygen directly to the lungs of seriously ill people and saves their lives. A vacuum cleaner and air conditioning have long been familiar in our everyday life.
Both of these devices use compressed atmospheric components: a vacuum cleaner draws particles of dust and mechanical impurities from various surfaces with a jet. The flow of cold gases from the air conditioner cools the room in the heat. These examples once again demonstrate the possibilities of how a person uses the properties of air in his life.