Why is oxygen heavier than air? Which gas is heavier than air under normal conditions?

12.03.2018

Really, natural gas is a cheap and accessible fuel. I brought a match and behold - thermal and even light energy. It is quite easy to manage and use.
But is everything so reliable and simple?

Natural gas is produced in gas fields, and it is supplied from the production site through gas pipelines to our gas stoves and heating devices. It can be simpler - to stoves and boilers. How good. Take it and use it!

Then, to raise the water, you need to overcome the pressure of the water column. High, i.e. normal atmospheric pressure. In the second case, when the water rises to 1 m, the plunger is also subjected to pressure 1 at a temperature higher, and the pressure acting from below comes from.

Therefore, it is necessary to overcome the pressure of the water column. Thus, hopes of obtaining an engine that does not consume energy are dissipated. Soak the fire with boiling water. Boiling water suffocates fires faster than cold water by absorbing the heat of the flame's evaporation and enveloping them in steam, thereby preventing air from entering. Wouldn't it be better if firefighters always had boiling water ready to put out fires?

So we take it and use it. They brought their actions to automaticity: light a match, bring it to the gas burner, open the tap... That's right, that's how it should be. Gas must not be allowed to escape without combustion, otherwise...

The main flammable component of natural gas is methane. This is one of the hydrocarbons about which there is so much fuss - political, economic... Its content in natural gas can be up to 98%. In addition to methane, natural gas also contains ethane, propane, butane. Non-flammable components include: nitrogen, carbon dioxide, oxygen, water vapor. By the way, it is interesting to know that the combustible elements of the periodic table in our nature are only carbon, hydrogen and partially sulfur. Nothing else is burning.

A fire pump will not be able to draw boiling water, since there must be 1-volt steam under its piston instead of rarefied air. The gas contained in the container. Container A contains compressed air at a pressure greater than 1 at room temperature. The pressure of the compressed gas is indicated on the mercury column on the manometer. When valve B opens, a certain amount of gas is released, and the mercury column of the manometer tube drops to a height corresponding to normal pressure. Some time later it was noticed that although the key remained closed, the mercury rose again.

Methane mixed with air is explosive in 5-15% of cases, i.e., when fire is introduced, the mixture instantly ignites and releases a large amount of heat. The pressure increases 10 times! I won’t explain what it is and what it looks like, believe the author - it’s scary!

Let's imagine (let it be a bad dream) that in a room with an internal volume of 100 cubic meters. it turned out to be from 5 to 15 cubic meters. natural gas (I note right away that the specific smell will be unbearable). And then someone in a nightgown, a nightcap and with a candle in his hands is heading there. He really wants to know what stinks so disgustingly... He doesn’t know! Won't have time...

Bubble at the bottom of the ocean. If there were a bubble shape near the ocean floor, at a depth of 8 km, would it rise to the surface? Mariotte's law states that the density of a gas is inversely proportional to pressure. Applying this law to the case considered, we can conclude that the density of air under a pressure of 800 atm will be 800 times higher than at normal pressure. The air around us is 770 times denser than water. For this reason, the bubbly air at the bottom of the ocean must be denser than water, so it cannot appear.

However, this conclusion follows from the erroneous assumption that Mariotte's law is still valid at a pressure of 800 at. Already at a pressure of 200 in air, 190 times are compressed instead of 200; at a pressure of 400 at. 315 times. The greater the pressure, the greater the difference from the value established by Mariotte's law. At a pressure of 600 in air it compresses 387 times.

Natural gas itself is colorless, tasteless and odorless. He'll be odorized! That’s right, they give everyone a well-known “aroma”, and the intensity of the smell is made so so that the human nose can sense gas when its volume is already 1%. This means that another 4% and a terrible dream with someone in a nightgown, a cap and a candle in their hands will become a reality...

Segner wheel in the void. Will the Segner wheel turn into a vacuum? Those who believe that the Segner wheel turns as a result of pressing a jet of water into the air, they will be sure that it cannot be turned in a vacuum. However, said artifact rotates for a different reason. Its movement is caused by an internal force, namely the difference in pressure that the water exerts on the open and closed ends of the tube. This excess pressure does not depend at all on the environment in which the device is located, be it vacuum or air.

Goddard successfully conducted a similar experiment in which the recoil force of firing a pistol under the bell of a vacuum pump is converted into a tiny merry-go-round. Rockets fly in outer space, pushed by the same recoil force that is created during the release of gases.

...At least put out the candle. And do not use any electrical appliances. The ignition temperature of natural gas is within 750 degrees C, and this is the temperature of any electrical spark or even the tip of a cigarette during a puff.

Open windows and doors faster - create a draft, such that the cap would be torn off, and to hell with this heat. Natural gas is approximately twice as light as air and it will quickly fly away into the atmosphere.
Call the gas service, the Ministry of Emergency Situations, the police, anywhere, they won’t be offended. Notify them if you smell gas. Don't forget to tell us your address. Be sure to talk to your neighbors. So what if you were left in just your nightgown, maybe they will be pleased...

Weight of dry and humid air. Which weighs more, one cubic kilometer of dry air or one of moist air, if the temperature and pressure are the same? Solution It is well known that a cubic meter of moist air is a mixture of one cubic meter of dry air and one of water vapor. Therefore, at first glance it appears that one cubic meter of moist air weighs more than other dry air, and that the difference is equal to the weight of the steam contained in the former. However, this conclusion is incorrect: moist air is lighter than dry air.

The reason is that the pressure of each of the components is less than that of the entire mixture; As pressure decreases, the weight of each unit volume of gas also decreases. Let's explain this in more detail. The total mass of one cubic meter of the mixture should be equal. That is, a cubic meter of air-steam mixture will be lighter than one of dry air.

Good luck to you, warmth and peace!

Gas is one of the states of matter. It does not have a specific volume, filling the entire container in which it is located. But it has fluidity and density. What are the lightest gases there are? How are they characterized?

Thus, at the same temperature and pressure, a cubic meter of moist air has a lower weight than one of dry air. Maximum vacuum. To what extent do the most efficient modern pumps cut through the air? What does "emptiness" mean? How many molecules will remain in a 1 liter container from which the air has been evacuated by the most efficient modern pump?

Readers who have never tried to calculate how many air molecules remain in a 1 cm 3 container by reducing the pressure of the air contained in it a thousand times are unlikely to be able to answer this question in any way. At a pressure of 1 to 1 cubic centimeter of air contains. When the pressure drops 1000 times more.

The lightest gases

The name “gas” was coined back in the 17th century because of its consonance with the word “chaos.” Particles of matter are indeed chaotic. They move in random order, changing trajectory every time they collide with each other. They try to fill all available space.

Gas molecules are weakly bonded to each other, unlike molecules of liquid and solid substances. Most of its species cannot be perceived with the help of the senses. But gases have other characteristics, for example, temperature, pressure, density.

Here is their chemical composition. Solution Of course, air molecules are subject to gravity, although they move constantly and at high speed. Earth's gravity reduces the directional velocity component from the Earth's surface, thereby preventing molecules that integrate the atmosphere from leaving the planet. To the question of why the molecules that make up the atmosphere do not rush towards the Earth? it is necessary to answer as follows: they do not stop striving for the earth's surface, but, being absolutely elastic, they bounce off their “relatives” who come towards them and the earth, always maintaining a certain height.

Their density increases as pressure increases, and as temperature increases they expand. The lightest gas is hydrogen, the heaviest is uranium hexafluoride. Gases always mix. If gravitational forces act, the mixture becomes inhomogeneous. The light ones rise up, the heavy ones, on the contrary, fall down.

The lightest gases are:

The height of the upper limit of the earth's atmosphere depends on the speed of the fastest molecules. Very few molecules have the speed seven times greater, which allows them to rise to heights. This fact explains the presence of “traces” of the atmosphere at an altitude of 600 km of the earth’s surface.

Gas that does not fill the entire container. Will gases always fill the space they are in? Can one gas occupy part of the ship, leaving another unoccupied? Solution We are accustomed to thinking that gas always occupies the entire volume of the container that contains it. That is why it is difficult to imagine under what conditions gas can occupy part of the ship, leaving the other part free. Then it would be a “physical” absurdity. But it didn’t take any work to mentally “create” such conditions for this paradoxical phenomenon.

hydrogen;
nitrogen;
oxygen;
methane;

The first three belong to the zero group of the periodic table, and we will talk about them below.

Hydrogen

Which gas is the lightest? The answer is obvious - hydrogen. It is the first element of the periodic table and is 14.4 times lighter than air. It is denoted by the letter H, from the Latin name Hydrogenium (giving birth to water). Hydrogen is the most abundant element in the Universe. It is part of most stars and interstellar matter.

For this reason, the gas does not always leave the container open to the empty space that surrounds it. This phenomenon can be observed in a vessel with a much lower height, for example, several tens of meters, in which there is little, in particular, heavy gas and at a fairly low temperature.

When reading this paragraph, the reader may get the following misconception: as above the lower vessel, the oil column is higher than above the upper one, the mercury will be shifted from the first to the second. In this case, it does not take into account the fact that not only oil, but also mercury, contained in a communicating tube communicating with both vessels, presses on the liquid of the lower container; its pressure is more noticeable to the latter than to the latter than to the other vessel. In general, the pressure differences of both oil columns and mercury columns should be compared.

Under normal conditions, hydrogen is absolutely harmless and non-toxic, odorless, tasteless and colorless. Under certain conditions, it can significantly change properties. For example, when mixed with oxygen, this gas easily explodes.

Can dissolve in platinum, iron, titanium, nickel and ethanol. When exposed to high temperatures, it transforms into a metallic state. Its molecule is diatomic and has high speed, which ensures excellent thermal conductivity of the gas (7 times higher than that of air).

It is easy to understand that the difference in the heights of the columns of both liquids is equal to one, but since mercury weighs much more than oil, the pressure of the former is more noticeable. Evapotranspiration and transpiration. Structure of a water molecule. Solid gaseous liquid. . Water has 2 densities.

Melting point: This is the T° at which a solid turns into a liquid, this T° corresponds to 0°C, in the case of water. The property is that some materials must conduct electric current. In the case of pure or distilled water, if certain conductivity tests are done, it results in it practically not conducting electricity, which means that its particles are not dissociated, that is, there is no presence of ions that are responsible for conducting electricity.

On our planet, hydrogen is found mainly in compounds. In terms of its importance and involvement in chemical processes, it is second only to oxygen. Hydrogen is found in the atmosphere and is part of water and organic substances in the cells of living organisms.

Oxygen

Oxygen is designated by the letter O (Oxygenium). It is also odorless, tasteless and colorless under normal conditions, and is in a gaseous state. Its molecule is often called dioxygen because it contains two atoms. There is its allotropic form or modification - ozone gas (O3), consisting of three molecules. It is blue in color and has many characteristics.

On the contrary, when it comes to drinking water, it leads to electricity as it contains many ions dissolved in it. For example, dissolved salt in water. This is a mixture of gases of a homogeneous type, i.e. one final physical phase is assessed. The air is mainly found in the lower layer of the atmosphere, which corresponds to the troposphere.

The atmosphere is divided into the following layers. Air consists of 78% nitrogen, 21% oxygen, 1% carbon dioxide, noble gases and water vapor. You can also find other components in the air, such as smoke, dust particles in suspension, ash, pollen, etc.

Oxygen and hydrogen are the most common and lightest gases on Earth. There is more oxygen in the crust of our planet, it makes up approximately 47% of its mass. In a bound state, water contains more than 80%.

Gas is an essential element in the life of plants, animals, humans and many microorganisms. In the human body, it promotes redox reactions, entering our lungs with air.

Normal state of oxygen: gaseous. Soluble in water, but very little. It's heavier than air. Chemical properties of oxygen. In living organisms, it reacts with carbon to form carbon dioxide and with hydrogen to form water. Oxygen is involved in all combustion reactions. Combustion is a chemical reaction that occurs between a fuel and an oxidizer during combustion, oxygen being the oxidizer.

Main application: medicine. It is used in industry, especially in steel production, as it eliminates contaminants. This is an excellent oxidizing agent. Due to its oxidizing ability, it is used in special programs. It is present in all burns.

Due to the special properties of oxygen, it is widely used for medical purposes. With its help, hypoxia, gastrointestinal pathologies, and attacks of bronchial asthma are eliminated. In the food industry it is used as a packaging gas. In agriculture, oxygen is used to enrich water for fish breeding.

Nitrogen

Like the two previous gases, nitrogen consists of two atoms and does not have pronounced taste, color or odor. The symbol for its designation is the Latin letter N. Together with phosphorus and arsenic, it belongs to the subgroup of pnictogens. The gas is very inert, which is why it received the name azote, which is translated from French as “lifeless.” The Latin name is Nitrogenium, that is, “giving birth to saltpeter.”

It is indispensable for the life of organisms. This is the main source of water and air purification. This is the closest layer of earth. It contains 90% of the atmospheric gases and is therefore the one that contributes almost the entire mass of the atmosphere. And in Ecuador it reaches 17 km. The troposphere is called the dirty layer because it is concentrated dust separated from desert and industrial activity.

All phenomena that affect climate occur in this layer. It is located above the troposphere and is about 50 km thick. There are no climatic phenomena due to the lack of air. Laotian gases are: nitrogen, oxygen and ozone. This layer contains the ozone layer, which helps filter ultraviolet rays. The ozone layer is found in its highest concentration, approximately 25 km away, in Ecuador and lowest at the poles.

Nitrogen is found in nucleic acids, chlorophyll, hemoglobin and proteins, and is the main component of air. Many scientists explain its content in humus and the earth's crust by volcanic eruptions that transport it from the Earth's mantle. In the Universe, gas exists on Neptune and Uranus, and is part of the solar atmosphere, interstellar space and some nebulae.

It is about 20 km thick. In this layer the density of gases is very low, and for this reason it was impossible to determine the T° of the exosphere, only the presence of hydrogen and helium gas was demonstrated. Carbon dioxide: a product of respiration and combustion. Characteristics: Non-toxic, but in high concentrations it causes asphyxia.

It is a colorless, odorless and tasteless gas. Small jet, so it is used to make fire extinguishers. It dissolves in water, which facilitates the formation of acid. Disadvantages: increased concentration in the air causes. Acidification of acid rain.

Humans use nitrogen mainly in liquid form. It is used in cryotherapy, as a medium for packaging and storing products. It is considered the most effective for extinguishing fires, displacing oxygen and depriving the fire of “fuel”. Together with silicon it forms ceramics. Nitrogen is often used for the synthesis of various compounds, for example, dyes, ammonia, and explosives.

Conclusion

Which gas is the lightest? Now you know the answer yourself. The lightest are hydrogen, nitrogen and oxygen, which belong to the zero group of the periodic table. They are followed by methane (carbon + hydrogen) and carbon monoxide (carbon + oxygen).

The lightest gases

The lightest gases are:

hydrogen;
nitrogen;
oxygen;
methane;

The first three belong to the zero group of the periodic table, and we will talk about them below.

Hydrogen

Oxygen

Gas is an essential element in the life of plants, animals, humans and many microorganisms. In the human body, it promotes redox reactions, entering our lungs with air.

Nitrogen

Conclusion

Probably, the question of what is heavier - air or carbon dioxide - can arise in any person. On the one hand, you have to constantly breathe air - without it, even a trained person cannot last longer than a few minutes. On the other hand, everyone knows from childhood that carbon dioxide is released when breathing. Therefore, let's look at this issue in more detail.

Air composition

Air, unlike carbon dioxide, is not one substance, but a complex mixture, which includes more than ten substances. And this is only normal air, not city air, which contains several dozen other ingredients dangerous to humans.

So, the largest share is nitrogen - the air consists of 76% of it. It does not support combustion and is not used for breathing.

But the next component is vital for all living things - oxygen. There is much less of it in the air, only 23%. But it is he who allows humans, animals, birds, fish and plants to live. Yes, yes, plants also breathe, although not everyone knows this.

The third gas in air is argon. There is already quite a bit of it, only 1.3 percent. It is also almost never used in wildlife, but is actively used by people in various fields of activity.

The fourth place is occupied by carbon dioxide. True, the amount is very small - only 0.046%. Imagine, all the factories, cars and living beings on the planet can hardly increase this indicator. Although, according to environmentalists, harmful production and deforestation lead to the fact that this figure is still increasing.

Air also consists of neon, krypton, methane, helium, hydrogen and xenon. The latter occupies only 0.00004% of the total mass. Other impurities are so insignificant that you can’t even talk about them.

What does carbon dioxide consist of?

Carbon dioxide is a separate substance. Its formula is CO2. Interestingly, unlike most chemical mixtures, in nature it does not exist at all in a liquid state. It occurs only in gaseous and solid forms, gradually changing from one state to another under certain conditions.

It easily transmits ultraviolet rays, allowing the Sun to heat the Earth. But infrared heat emanating from the surface of the planet does not transmit. Because of this, it accumulates, and gradually the temperature around the world rises. This is called the greenhouse effect, because of which environmentalists around the world are sounding the alarm.

Density comparison

Scientists love to weigh, compare and analyze everything. Of course, air with carbon dioxide did not escape this fate. Through complex calculations using modern equipment, it was possible to accurately determine the density of both substances. Knowing them, you can determine what is heavier - air or carbon dioxide, and what is lighter.

For carbon dioxide, this figure is 1.977 kilograms per cubic meter. Ordinary air has less - only 1.204 kg/m3. However, it is worth considering that such clean air is rarely found in nature - usually it also contains dust, moisture and various impurities.

But from a scientific point of view, it is the benchmarks that should be considered. Therefore, we can say with confidence how many times carbon dioxide is heavier than air - almost 1.64 times.

Why are they important?

The importance of air has already been discussed above. But any educated person knows perfectly well that without him, nothing living on planet Earth could survive in principle.

But what can we say about carbon dioxide? Paradoxically, if he suddenly disappears from the Earth, then humanity will die out surprisingly quickly. The point is not even that carbon dioxide is actively used in various industries. It is simply necessary for plants.

As mentioned above, any living organisms breathe oxygen. And plants are no exception. However, they also need carbon dioxide. After all, in the light, the process of photosynthesis is actively occurring in green cells. It involves the breakdown of CO2 cells into carbon and oxygen. The latter is released into the atmosphere (or into the water, if we are talking about green algae, which also undergoes photosynthesis), and the carbon is used to build new cells and plant growth. If all the carbon dioxide disappears, then the process of photosynthesis will stop. This means that plants will stop growing, animals and people will be left without food, which will very quickly lead to famine and the extinction of all humanity.

Where is mass difference used?

Knowing what is heavier - air or carbon dioxide, we can assume that the latter always tends downwards. And this can be used in practice. For example, this effect is used by divers when diving with a cap. The supply of air here is limited, and if carbon dioxide were mixed with it evenly, breathing would be difficult. But its excess is predominantly released and sinks lower, allowing a person to breathe easily.

This effect is also used in firefighting. Special fire extinguishers - carbon dioxide - are filled with carbon dioxide. When liquefied gas escapes from the bell, it immediately expands approximately 400-500 times, at the same time cooling by 72 degrees. This alone is enough for many burning objects to go out. But heavy gas spreads across the floor and burning objects, displacing air. Since CO2 does not support combustion, the flame, left without oxygen supply, simply goes out.

Conclusion

This is where we can end the article. Now you know what is heavier - air or carbon dioxide, and by how much. At the same time, you learned about the basic properties of both substances, their importance in nature, as well as the use of density differences in human life. We hope you find this information useful.

Carbon monoxide (CO) is a toxic, colorless and odorless combustion product commonly known as carbon monoxide. Whether this substance is heavier or lighter than air depends on external conditions. Most often it is formed during the combustion of carbon in an oxygen-poor environment. If a fire occurs in a closed, unventilated room, people die from poisoning.

Carbon monoxide is colorless and odorless, so it cannot be smelled

Properties of carbon monoxide

Carbon monoxide has been known to people since ancient times because of its toxic properties. The total use of stove heating often led to poisoning and death. There was a danger of burning for those who covered the chimney damper at night when the coals in the firebox were not yet burned out.

The insidiousness of carbon monoxide is that it is colorless and odorless. Carbon monoxide is slightly less dense relative to air, causing it to rise. During fuel combustion, carbon © is oxidized by oxygen (O), and carbon dioxide (CO2) is released. It is harmless to humans and is even used in the food industry, in the production of soda and dry ice.

This video will tell you how to survive and provide first aid to a victim of carbon monoxide poisoning:

When a reaction occurs with insufficient oxygen, only one oxygen molecule is added to each carbon molecule. The output is CO - toxic and flammable carbon monoxide.

Toxicity and symptoms of poisoning

Often, exceeding this indicator can be found in large cities, which, of course, quite possibly may be the reason for people’s poor health

The toxicity of carbon monoxide is due to its ability to form a stable compound with hemoglobin in human blood. As a result, oxygen starvation of the body occurs at the cellular level. Without timely medical care, irreversible changes in tissues and death are possible.

The central nervous system is primarily affected. Damage to nerve tissue as a result of hypoxia leads to the development of neurological disorders that may appear some time after poisoning.

Carbon monoxide poisoning is an acute pathological condition that develops as a result of carbon monoxide entering the human body.

You can get carbon monoxide poisoning in the following situations:

In case of fire in an enclosed space.
Chemical production in which carbon monoxide is widely used.
When using open gas appliances and insufficient ventilation.
Staying on a busy highway for a long time.
In the garage with the engine running.
If the stove is used incorrectly, if the dampers close before all the coals have burned out.
Smoking a hookah can cause symptoms of poisoning.

The specific gravity of air and carbon monoxide is almost the same, but the latter is slightly lighter, due to which it first accumulates near the ceiling. This property is used when installing sensors that signal danger. They are located at the highest point of the room.

It is very important to recognize poisoning in a timely manner and take measures to save yourself and others. There are a number of symptoms associated with carbon monoxide toxicity:

pain and heaviness in the head;
cardiopalmus;
increase in pressure;
a knocking sound is heard in the temples;
a kind of dry cough;
nausea sets in;
vomiting begins;
pain in the chest area;
the skin and mucous membranes become noticeably red;
Hallucinations are possible.

As preventive measures to avoid carbon monoxide poisoning, you should: regularly check, clean and timely repair ventilation shafts, chimneys and heating appliances

Finding yourself or other similar symptoms indicates the initial stage of poisoning.

Moderate severity is characterized by drowsiness and severe tinnitus, as well as motor paralysis, while the victim does not yet lose consciousness.

Symptoms of severe intoxication:

the victim loses consciousness and falls into a coma;
urinary and fecal incontinence;
muscle cramps;
constant breathing problems;
blue color of skin and mucous membranes;
dilated pupils and lack of reaction to light.

The person cannot help himself in any way and death finds him at the scene of the incident.

First aid and treatment

Regardless of the severity, carbon monoxide injury requires immediate medical attention. If you are able to walk on your own, you must immediately leave the affected area. Victims who are unable to move are put on gas masks and urgently evacuated from the affected area.

In case of carbon monoxide poisoning, you must immediately call an ambulance

First aid consists of the following actions:

It is necessary to free a person from restrictive clothing.
Warm up and let you breathe pure oxygen.
Irradiate with ultraviolet radiation using a quartz lamp.
If necessary, artificial respiration and cardiac massage are performed.
Give ammonia a whiff.
Take him to the nearest hospital as quickly as possible.

In the hospital, therapy will be carried out aimed at removing the toxin from the body. Then a full examination is carried out to identify possible complications. After this, a series of restoration measures are carried out.

To avoid troubles and tragedies associated with intoxication, It is recommended to follow simple preventive measures:

Victims of carbon monoxide poisoning must be taken to fresh air or the room thoroughly ventilated.

Monitor the cleanliness of the internal lumen of chimneys.
Always check the condition of air dampers in stoves and fireplaces.
It is good to ventilate rooms with open gas burners.
Follow safety rules when working with a car in a garage.
If exposed to carbon monoxide, take an antidote.

Air is heavier than carbon monoxide by molar mass per unit. Their specific gravity and density differ little. Carbon monoxide is harmful to the human body. Poisoning statistics show that the peak of accidents occurs in the winter.

There is a common phrase that a person cannot live without something (fill in your own words), like without air - and this is absolutely true. It is he and oxygen that are a necessary condition for the existence of the predominant number of living beings on Earth.

What is oxygen and air

Oxygen is a gas whose molecule consists of two oxygen atoms.
Air is a mixture of gases that form the Earth's atmosphere.

Comparison of oxygen and air

What is the difference between oxygen and air?
Oxygen is a gas that has no color, taste or odor. The oxygen molecule consists of two atoms. Its chemical formula is written as O2. Triatomic oxygen is called ozone. One liter of oxygen is equal to 1.4 grams. It is slightly soluble in water and alcohol. In addition to gaseous, it can be in a liquid state, forming a pale blue substance.
Air is a mixture of gases. 78% of it is nitrogen, 21% is oxygen. Less than one percent comes from argon, carbon dioxide, neon, methane, helium, krypton, hydrogen and xenon. In addition, there are water molecules, dust, grains of sand, and plant spores in the air. The mass of air is less than the mass of oxygen of the same volume.
Oxygen was discovered in 1774 by Englishman Joseph Priestley by placing mercuric oxide in a closed vessel. The term “oxygen” itself was introduced into use by Lomonosov, and put “in place No. 8” by the chemist Mendeleev. According to its periodic table, oxygen is a non-metal and the lightest element of the chalcogen group.
In 1754, the Scot Joseph Black proved that air is not a homogeneous substance, but a mixture of gases, water vapor and various impurities.
Oxygen is considered the most abundant chemical element on Earth. Firstly, due to its presence in silicates (silicon, quartz), which make up 47% of the earth’s crust, and another 1,500 minerals that make up the “terra firma”. Secondly, due to its presence in water, which covers 2/3 of the planet's surface. Thirdly, oxygen is an unchanged component of the atmosphere, more precisely, it occupies 21% of its volume and 23% of its mass. Fourthly, this chemical element is part of the cells of all terrestrial living organisms, being every fourth atom in any organic matter.
Oxygen is a prerequisite for the processes of respiration, combustion and decay. Used in metallurgy, medicine, chemical industry and agriculture.
Air forms the earth's atmosphere. It is necessary for the existence of life on Earth; it is a prerequisite for the processes of respiration, photosynthesis and other life processes of all aerobe creatures. Air is needed for the fuel combustion process; Inert gases are extracted from it by liquefaction.

TheDifference.ru determined that the difference between oxygen and air is as follows:

Oxygen is a homogeneous substance; air consists of a number of components.
Pure oxygen is heavier than air of equal volume.
Air is only part of the atmosphere, and oxygen is an essential component of the hydrosphere, lithosphere, atmosphere and biosphere.