Gas is one of the aggregate states of matter. It is widespread both on Earth and beyond. Gases can be freely found in nature or released during chemical reactions. They are involved in the respiration of most living beings on the planet, and man has learned to use them in everyday life, industry, medicine and other fields of activity.
Gas - what is it?
In its state, gas is very similar to steam. It is a formless ephemeral substance that fills any space. Unlike vapor, it does not change into a liquid when its pressure is increased.
Its name means "chaos" and was coined by the Dutch scientist Jan van Helmont. Gas molecules are very weakly bound, they move as they like, sometimes colliding and changing their trajectory. This state of affairs reminded Helmont of primeval chaos.
Gas is the basic state of matter in the universe. It forms nebulae, stars, and planetary atmospheres. The air shell of the Earth also consists of gas, or rather a mixturevarious gases, dust, water and aerosols.
Basic Features
Most gases do not have pronounced physical characteristics. They are colorless and odorless. Describing the qualities of a gas is more difficult than any mineral that we can clearly see and touch. To characterize them, the following parameters are used: temperature, volume, pressure and number of particles.
Gases do not have specific outlines and take the form of the object they are in. In this case, the substances do not form any surface. They always mix. The same amount of gas will fill both a small jar and a large room. But in the second case, the distance between the molecules will greatly increase, and its concentration in the air will be less.
The pressure of a substance is the same at any point when it is not affected by gravitational forces. With their influence, the pressure and density of gases decreases with height. It feels great in the mountains, where the air becomes rarefied at high altitudes.
As the temperature increases, gases expand, and the speed of molecules increases. On the contrary, they shrink with increasing pressure and density. They conduct heat and electricity poorly.
Combustion
According to the ability to enter into a combustion reaction, gases can be divided into oxidizers, neutral and combustible. The least active substances are neutral or inert gases: argon, xenon, nitrogen, helium, etc. They interact the worst with compounds and materials, and are also capable ofstop and limit combustion.
Oxidizing agents include oxygen, air, nitrogen oxide and dioxide, chlorine, fluorine. By their nature, they are not combustible, but they perfectly support this reaction. Under certain conditions, they can spontaneously ignite and even explode, for example, when combined with grease or grease.
Combustible gases are ammonia, methane, carbon monoxide, propane, propylene, ethane, ethylene, hydrogen and others. In nature, they can be in a calm state. But, mixed in the right amount with oxygen or air, they ignite. This does not happen if there is too little or too much oxidizing agent. So, for the complete combustion of methane gas (1 kg), about 17 kg of air is needed.
Interesting facts
- Many gases are very light. The record holder among them is hydrogen, which is 14 times lighter than air. One of the heaviest at room temperature is radon. Of the inorganic compounds, the heaviest is tungsten hexafluoride.
- The most inert and inactive gas is helium. It is the second lightest after hydrogen, but it is not explosive, which is why it was used for airships.
- In outer space, hydrogen is the most common gas.
- Oxygen is the most common in the earth's crust, radon is the least.
- Under normal conditions, not all gases are colorless. Ozone is blue, chlorine is yellow-green, and nitrogen is red-brown.
