The gases are substances that are in the gaseous state at normal temperature and pressure (NTP: 20 ° C, 1 atmosphere). In this state of aggregation, the particles that form them are so far apart that they flutter around the container that contains them. If they are not in a container, they will travel freely depending on their weight and the influence of the environment, such as the force of the wind.
Gases differ from solids and liquids by their unique characteristics: the distances between their atoms or molecules are relatively large , and they have very small attractive forces . In lighter gases, such as hydrogen and helium, these forces are negligible. They have a very high kinetic energy , they tend to move without stopping and when confined they take the geometric shape of the container . This is why balloons have taut walls when inflated.
10 examples of types of gases
After having explained their general properties, it is necessary to detail the classification of gases. These substances are going to be divided according to their behavior . This characteristic includes their physical and chemical responses, and perfectly marks the differences between each type of gas. Thus, the types of gases are:
- Ideal gases
- Real gases
- Inert gases
- Reactive gases
- Combustible gases
- Oxidizing gases
- Toxic gases
- Corrosive gases
- Liquefied gases
- Oxidizing gases
Types of gases, inert
Ideal gases are those that under certain conditions obey the ideal gas law : PV = nRT , an expression that comes from the general gas law and describes a constant relationship between their properties pressure (P), volume (V), mass in mol (n) and temperature (T).
They are called ideals because they do n’t really behave that way . This concept is only used in laboratory, engineering and academic calculations, for convenience, but does not represent what actually happens.
The term “real gases” refers to all gases . When studying them, it is essential to have an equation that describes how their properties are related to each other. That is, how the temperature changes when the pressure increases, or what change in volume there is when introducing more mass, for example, with the highest possible accuracy.
Depending on the case, the Berthelot equation , the Van der Waals equation , the compressibility factor , the virial equation or the Redlich-Kwong equation , among others, will be used. Each has a different precision, but is useful in circumstances where the others do not. They rely on tables and diagrams to know the factors that compose them.
Inert gases are all those that, due to the stability of their atoms or molecules, do not tend to react or it is very difficult for them to do so. The main inert gases are the noble gases , which make up group VIIIA of the Periodic Table of Chemical Elements. These are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and radon (Rn).
On the other hand, nitrogen N 2 , which has a triple bond between its two N≡N atoms , is also considered inert . This makes them so strongly attracted that they can hardly get involved in a chemical reaction. Only a very high temperature can cause this bond to break.
That is why there is 79% nitrogen in the atmosphere , to buffer the presence of oxygen, a gas that helps us to breathe, but that in excess can cause fires on the planet.
Reactive gases are all those gaseous substances capable of participating in a chemical reaction , interacting with different ones and creating products. Within this category are combustible gases, oxidizing gases, toxic gases, corrosive gases and oxidizing gases, which have a specific chemical behavior.
Combustible gases are those that when a spark or an enormous amount of heat is induced, react by emitting a flame and heat energy , which can be used to heat water and generate steam, cook food, join metals by means of a torch, among other purposes. The most important are methane (CH 4 ), propane (C 3 H 8 ), butane (C 4 H 10 ) and acetylene (C 2 H 2 ).
Oxidizing gases are those that intervene in a combustion reaction to preserve it and allow it to continue to occur , until the fuel has been used up in the greatest possible proportion. The oxidizer par excellence is oxygen (O) , which has the highest oxidizing power to promote the continuity of the reaction in the fuel.
Toxic gases are those that, once they come into contact with the human body , alter its functions to the point of causing disease and causing harm. These consequences can be caused by long-term exposure to these gases or by accidentally breathing them in large doses. Ammonia, for example, (NH 3 ), is dangerous because, even in a small concentration, it causes sudden and very dangerous respiratory damage.
Corrosive gases are those that when they come into contact with the skin or the human respiratory system, begin to injure and wear down the tissue . This due to its oxidizing action. They attack cells in the skin and airways, initially causing bleeding. Its proximity can be detected from when you feel burning in the mentioned areas.
Liquefied gases are those that have been confined in a pressurized container . It is due to this great pressure that its particles will be sufficiently united to become a liquid state. When they are expelled from that container, generally by means of a valve, they are already at the mercy of atmospheric pressure and are released in a gaseous state.
Oxidizing gases are those capable of releasing electrons from other substances. They are used to counteract reducing agents, which in turn contribute electrons. In addition, they work as chemical reagents in the laboratory, to study certain reactions. The oxidizing gases par excellence are oxygen (O 2 ) and ozone (O 3 ).