What is in the air? What is the composition of air?

The composition of air and its volume fraction: nitrogen (78%), oxygen (21%), noble gas (carbon dioxide (other gases and impurities). Other gases include water vapor such as helium, neon, argon, krypton, xenon, and radon as noble gases.

Air is a mixture of many gases. Its constant components are oxygen, nitrogen, and rare gases such as argon, neon, helium, krypton, and xenon, while the variable components are carbon dioxide and water vapor, and their content in the air varies slightly within a small range depending on the location and temperature on the earth. As for the indefinite components of the air, it varies from region to region, for example, sulfur dioxide is contained near metallurgical plants, chlorine is found near chlor-alkali plants, and so on.

In addition, there are trace amounts of hydrogen, ozone, nitrous oxide, methane and, to a lesser extent, dust in the air.

Experiments have shown that the percentage of constant components in the air is almost constant up to 100 km above the ground. In terms of volume content, oxygen accounts for about about it, nitrogen about about it, argon about about it, and the reason why the main components of nitrogen and oxygen in the air are relatively constant is the result of the mutual compensation of various changes in nature.

The respiration of animals and plants, the burning of materials, the decay of animals and plants, and the rust of steel all consume a lot of oxygen, but green plants also need to photosynthesize in the sun, that is, inhale carbon dioxide in the air and release oxygen at the same time. Experiments have shown that the total amount of oxygen released by a plant is about 20 times more than the amount of oxygen it needs to breathe. This is the reason why the amount of oxygen remains relatively balanced.

Nitrogen is needed for plant growth. The ** of nitrogen is the nitrogen in the air. Natural nitrogen fixation mainly relies on lightning to oxidize nitrogen into nitric oxide, which is further oxidized into nitrogen dioxide, which is dissolved in rainwater to form nitrite and nitric acid.

into the soil to convert into nitrite and nitrate. It is estimated that about 40 million tonnes of nitrogen can be fixed from the atmosphere each year through this pathway, and a small amount of nitrogen is fixed by rhizobia in legumes; The main way of artificial nitrogen fixation is the synthesis of ammonia from nitrogen. The fixed nitrogen can be broken down into nitrogen by a class of microorganisms called denitrifying bacteria and returned to the atmosphere.

In this way, another cycle in nature is completed, the nitrogen cycle, so that the amount of nitrogen in the atmosphere is almost constant.

The components contained in it are 78 08 for nitrogen, 20 95 for oxygen, 0 93 for argon, 0 03 for carbon dioxide, and trace amounts of noble gases, such as helium, neon, krypton, xenon, etc. Ozone, nitrogen oxides, nitrogen dioxide.

Air, colorless, odorless, the main components are nitrogen and oxygen, as well as a very small amount of radon, helium, neon, argon, krypton, xenon and other inert gases and water vapor, carbon dioxide and dust.

Air refers to the mixture of gases in the earth's atmosphere, so air belongs to the mixture, which is mainly made up of nitrogen.

Oxygen, noble gases.

helium, neon, argon, krypton, xenon, radon), carbon dioxide.

and other substances (such as water vapor, impurities, etc.).

where the volume fraction of nitrogen.

About 78%, the volume fraction of oxygen is about 21%, the volume fraction of noble gases (helium, neon, argon, krypton, xenon, radon) is about, the volume fraction of carbon dioxide is about annual data), and the volume fraction of other substances (such as water vapor, impurities, etc.) is about.

The composition of air is not fixed, and as the altitude changes, the air pressure changes, and the proportion of air composition also changes.

But air was long thought to be a single substance, until later the French scientist Lavoisier.

Experiments first led to the conclusion that air is composed of oxygen and nitrogen. At the end of the 19th century, scientists.

Through a large number of experiments, it was found that there are rare gases such as helium, argon, and xenon in the air.

Air is made up of a mixture of many different gases. Oxygen is an essential gas for aerobic respiration in animals and plants, and carbon dioxide is the raw material for photosynthesis in green plants. Flowers and trees in nature inhale carbon dioxide in sunlight to produce the oxygen needed by humans and other animals, which is the process of "photosynthesis".

The main components of air are nitrogen and oxygen, as well as very small amounts of radon, helium, neon, argon, krypton, xenon and other inert gases and water vapor, carbon dioxide and dust.

Nitrogen elemental nitrogen is a colorless and odorless gas under normal conditions, and the gas density under the standard condition is that when nitrogen is cooled to a standard atmospheric pressure, it becomes a colorless liquid, and when it is cooled to, the liquid nitrogen becomes a snow-like solid.

The solubility of nitrogen in water is very small, and at room temperature and pressure, only about one volume of nitrogen is dissolved in 1 volume of water. It is a gas that is difficult to liquefy. The solubility in water is very small, at 283K, one volume of water can dissolve about the volume of N2.

Nitrogen liquefies into a white liquid at very low temperatures, and when the temperature is further reduced, it forms a white crystalline solid.

Air is a mixture, and its composition is complex. The constant composition of the air is nitrogen, oxygen and noble gases, which are almost unchanged, mainly as a result of the mutual compensation of various changes in nature. The variable components of air are carbon dioxide and water vapor.

The adventitious composition of the air varies completely from region to region. For example, the air near the factory may contain ammonia and acid vapor depending on the production project. In addition, the air contains very small amounts of hydrogen, ozone, nitrogen oxides, methane and other gases.

Dust is a more or less suspended impurity in the air. In general, the composition of air is generally relatively fixed.

According to scientists, in dry air (calculated by volume) there are about 78 nitrogen, about 21 oxygen, about inert gas, about carbon dioxide, and about other impurities.

Of course, the composition of air is not fixed, and as the altitude changes, the air pressure changes, and the composition ratio of the air also changes.

Oxygen is needed for combustion, and when the lid is closed, the oxygen in the air in the pot is quickly used up and the fire is extinguished.

Under normal conditions, nitrogen is chemically inactive, so it is often used as a protective gas. For example, when welding metal, nitrogen is used to protect the metal from oxidation; Fill the bulb with nitrogen to prevent the tungsten filament from oxidizing or volatilizing; Food, such as grain, canned food, and fruits, is also commonly used as a protective gas with nitrogen to prevent food from rotting; In medicine, liquid nitrogen is often used to cool the scalpel and make it a "cold knife". Doctors use a "cold knife" to perform the operation, which can reduce bleeding or no bleeding, and the patient can be faster after the surgery**.

In high-tech fields, liquid nitrogen is commonly used to manufacture low-temperature environments, for example, some superconducting materials are treated with liquid nitrogen at low temperatures to obtain superconducting properties.

Nitrogen is also the "basis of life", it is not only the raw material for crops to make chlorophyll, but also the raw material for crops to make protein, according to statistics, the world's crops, in a year, take in about 40 million tons of nitrogen from the soil.

Cut a handful of rustless iron filings from the iron, wet them and sprinkle them on a piece of wood so that the chips float in a basin of shallow water. Then use a large glass upside down in the water to cover the wood chips. After standing for three or four days, you will see rust on the iron filings, and the water in the basin has risen slightly.

This means that there is less air in the cup, because a part of the oxygen and iron in the air is synthesized into iron oxide (i.e. rust).

Air is a mixture that is made of.

Molecules of oxygen, nitrogen, carbon dioxide, etc., and molecules such as nitrogen and oxygen in the air are evenly mixed together.

Nitrogen and itching are dominant.

Pristine atmosphere. It is mainly based on carbon dioxide, carbon monoxide and methane.

Nitrogen 78%, oxygen 21%, noble gases.

Carbon dioxide, other gases and impurities occupy.

The main components of air are as follows:

1. Nitrogen: The earth's atmosphere contains 78% nitrogen;

2. Oxygen: The earth's atmosphere contains 21% oxygen;

4. Other gases and impurities: other gases and impurities contained in the air;

5. Impurity gas: composed of sulfur dioxide, celery dioxide, nitrogen, ozone, etc.;

6. Rare gases: Rare gases contained in the air.