Gas is one of the aggregate states of matter.It is widespread both on Earth and beyond. Gases can freely be in nature or released in the course of chemical reactions. They participate in the breath of most living things on the planet, and man has learned to apply them in everyday life, industry, medicine and other fields of activity.
In its state, the gas is very similar to steam.It is a formless ephemeral substance that fills any space. Unlike steam, it does not pass into the liquid when its pressure increases.
Its name means "chaos" and it was coinedDutch scientist Jan van Helmont. Molecules of gases are very weakly bound, they move as you like, sometimes colliding and changing their trajectory. Such a state of things reminded Helmont of primordial chaos.
Gas is the basic state of matter inThe universe. It forms nebulae, stars and atmospheres of planets. The Earth's air shell also consists of gas, more precisely a mixture of various gases, dust, water and aerosols.
Most gases do not have pronouncedphysical characteristics. They do not have color and smell. It is more difficult to describe the quality of gas than any mineral that we clearly see and can touch. To characterize them, use such parameters: temperature, volume, pressure and number of particles.
Gases do not have specific outlines and acquirethe form of the object in which they are. In this case, the substances do not form any surface. They always mix. The same amount of gas will fill up both a small jar and a large room. But in the second case the distance between the molecules will increase greatly, and its concentration in the air will be less.
The pressure of the substance is the same at any point, whenthe gravitational forces do not act on it. With their influence, the pressure and density of gases decrease with altitude. This is perfectly felt in the mountains, where at high altitudes the air becomes sparse.
As the temperature increases, the gases expand, and the velocity of the molecules increases. With increasing pressure and density, they, on the contrary, are compressed. They conduct heat and electricity badly.
By the ability to react with combustion gasescan be divided into oxidizers, neutral and combustible. Neutral or inert gases, argon, xenon, nitrogen, helium, etc., are the least active substances. They react poorly with compounds and materials, and are also capable of stopping and limiting combustion.
Oxidants include oxygen, air, oxide andnitrogen dioxide, chlorine, fluorine. By their nature they are not flammable, but they perfectly support this reaction. Under certain conditions, they can self-ignite and even explode, for example, when combined with grease or grease.
Flammable gases are ammonia, methane, monoxidecarbon, propane, propylene, ethane, ethylene, hydrogen and others. In nature, they can be in a calm state. But, mixing in the right amount with oxygen or air, ignite. This does not happen if the oxidant is too little or too much. So, for the complete combustion of methane gas (1 kg), about 17 kg of air is needed.
