Examples of gases are as follows: oxygen, hydrogen, helium etc. It is not a new phenomenon that gases are one of four states of matter. Gases are made up of molecules that are further made up of individual atoms. Those atoms may be the same or different thereby forming elements and compounds respectively. The properties associated with the gases lie between the liquid and plasma states.
All the physical characteristics of gases and the compositions are based on their intermolecular forces and intermolecular spaces between the constituents. Gases have very wide spaces between them due to the dominance of intermolecular separation over intermolecular forces as compared to liquid and solids. That is the reason why gases cannot be held or put into a shape like solids and liquids. All of these properties related to gases are governed by temperature and pressure which are inversely proportional to each other in the case of gases.
Figure 1: Description of Gas molecules
Gases exist in different types and have many examples. Examples of gases can be categorized in different contexts. The two categories in which examples of gases are categorized are −
Gases of Homoatomic molecules
Gases of Heteroatomic molecules
Homoatomic gases as the name suggests are gases that consist of only a single type of atom and made up of the same element. These are also denoted as elemental gases. Homoatomic gases exist under standard temperature and pressure conditions. Due to changes in pressure and temperature, the gases can change their composition. Gases of homoatomic molecules are divided into three types depending upon the number of atoms involved.
Monatomic gases
Diatomic gases
Triatomic gases
Figure 2: Example of Homoatomic gases
Monatomic Gases
Monatomic gases are those homoatomic gases which are made up of single atom. The composition of monatomic gases is very simple in the context of thermodynamic properties due to the absence of rotational and vibrational constants and due to the involvement of a single element. The common examples of monatomic gases are the noble gases and vapors of certain metals. These are as follows −
Helium (He)
Neon (Ne)
Argon (Ar)
Krypton (Kr)
Xenon (Xe)
Radon (Rn)
Sodium vapor (Na)
Potassium vapor (K)
Diatomic Gases
Diatomic gases are evidenced from the name, which involves the bonding of two same or different elements. Under the category of homoatomic gases, these are considered homonuclear diatomic gases. Diatomic gases are usually made up of nonmetals and are formed through covalent bonding. Covalent bonding is a chemical bonding type that involves sharing of electrons.
In the case of homonuclear diatomic gases, the covalent compounds or gases formed are non-polar covalent gases. This is because the same atoms are bonded to each other which does not involve a difference in the charges and hence the absence of net dipole moment. Unlike monatomic gases, these are not simple and the change in temperature and pressure leads to changes in their composition as well. Diatomic gases are not considered as good conductors of electricity or heat. Examples of homonuclear diatomic gases are −
Hydrogen gas $\mathrm{(H_2)}$
Nitrogen gas $\mathrm{(N_2)}$
Oxygen gas $\mathrm{(O_2)}$
Fluorine gas $\mathrm{(F_2)}$
Chlorine gas $\mathrm{(Cl_2)}$
Bromine gas $\mathrm{(Br_2)}$
Triatomic Gases
As the name suggests, triatomic gases comprises bonding between the three atoms. The definition is flexible and like diatomic gases, these may also be homonuclear and heteronuclear. Here, only the homonuclear part is discussed. It is very well known that the most common homonuclear triatomic gas comprises of three oxygen atoms. There are many other homonuclear triatomic gases as well but these are not stable and eventually break into cations or other stable products. So the stable homonuclear triatomic gas is −
$\mathrm{Ozone\:(O_3)}$
Heteroatomic gases are made up of molecules of different atoms. Like homoatomic molecules, these are also divided into mono, di, and triatomic gases of heteronuclear origin. Heteroatomic gases are also called mixed gases as these are made up of different types of atoms. The bonding in heteroatomic gases is covalent, electrovalent, or dative. Hetero atomic gases depending upon its diversity in bonding and the type of atoms involved are classified into organic or inorganic gases. Various examples of heteroatomic gases of varied categories are mentioned below −
Air (Combination of oxygen, carbon dioxide, nitrogen, and other gases)
Carbon dioxide $\mathrm{(CO_2)}$
Carbon monoxide $\mathrm{(CO)}$
Acetylene $\mathrm{(C_2H_2)}$
Butane $\mathrm{(C_4H_{10})}$
Dimethyl ether $\mathrm{(C_2H_6O)}$
Ammonia $\mathrm{(NH_3)}$
Hydrogen sulfide $\mathrm{(H_2S)}$
Methane or Natural gas $\mathrm{(CH_4)}$
Nitrous Oxide $\mathrm{(N_2O)}$
Ethane $\mathrm{(C_2H_6)}$ and many more.
Figure 3: Example of heteroatomic gases
There are certain gases are not good for inhalation and may be dangerous and even deadly for the human body. Accidental breathing of toxic gases or even mild exposure can lead to the death of the person and in some cases; it could make a person feel light-headed and nauseous. People working in heavy industry or chemical manufacturing plants should be aware of the toxic gases and should take necessary measures while working. The list of toxic gases examples is discussed below −
Vinyl Chloride $\mathrm{(C_2H_3Cl)}$
Trichlorosilane $\mathrm{(SiHCl_3)}$
Trimethylamine $\mathrm{(C_3H_9N)}$
Sulfur dioxide $\mathrm{(SO_2)}$
Ozone $\mathrm{(O_3)}$
Osmium tetroxide $\mathrm{(OsO_4)}$
Hydrogen chloride $\mathrm{(HCl)}$
Hydrogen Sulphide $\mathrm{(H_2S)}$
Phosphine $\mathrm{(PH_3)}$
Phosgene $\mathrm{(COC_{l2})}$
Tungsten hexafluoride $\mathrm{(WF_6)}$
Formaldehyde $\mathrm{(CH_2O)}$
There are a variety of examples of gases that are important in sustaining life and its working on earth. Gases are of a variety of types and can belong to different categories. The list of examples of gases is endless. The physical and chemical properties associated with gases and their behavior makes them useful in a variety of applications. Gases are found in the usage of a variety of environments and conditions.
The natural usages of gases which play the role of basic elements for survival on earth are discussed. Air is required for breathing. Various biogeochemical cycles which balance the ecosystem are fulfilled only with the existence of gases. The growth of crops and maintenance of food production are fulfilled by gases that have a good nitrogen component in them. For instance growth of leguminous plants is possible only by conversion of atmospheric nitrogen gas into nitrates which are further used by the bacteria for the proper growth of the plants.
In Industries, the gases are manufactured at a commercial scale to aid different processes and sectors. These gases are called Industrial gases. Both organic and inorganic industrial gases are used in a variety of industrial processes like steel making, petrochemical analysis, semiconductor industry, medical industry, fertilizer production, H2 analysis industry, etc.
In nutshell, gases are an integral part of our living and in the smooth functioning of life on earth. It is not of significance for only human life existence but also to maintain the desired ecological balance and sustainability. Commercially, gases are a boon for a variety of sectors and industries. Though we are not able to enclose it due to its properties, its existence, and usage cannot be denied.
Q1. What are gas laws? Explain briefly all the gas laws.
Ans. Gas laws are the group of laws that look out for different behavioral changes in gases based on changes in their volume, pressure, temperature, and the number of moles of the gas. Four gas laws are established with the relation between all the factors responsible for the modification in gas’s behavior. These laws are −
Boyle’s Law: Establish the relationship between pressure and volume.
Gay Lussac’s Law: Exhibit the relationship between pressure and temperature.
Charles’s Law: Defines the relationship between volume and temperature
Avogadro’s Law: Define the relationship between volume and amount
Q2. Discuss briefly Ideal Gases.
Ans. An ideal gas is a theoretical concept that works under standard temperature and pressure conditions where the gases are not subjected to outside environmental conditions. The ideal gases follow the ideal gas equation
$$\mathrm{PV = nRT}$$
In the real world, no gas is an ideal gas but under certain standard pressure and temperature conditions, noble gases, N2, and O2 show ideal gas-like behavior for a certain time.
Q3. How is the pressure on the gas generated?
Ans. The pressure on the gas is generated when its molecules collide with each other and with the walls of the container. The collisions transfer a small amount of force and generate momentum. Momentum usually depends upon the speed which further depends on the temperature increase. Hence more the temperature increases, the more will be the speed and momentum and the more will be pressure exerted by the gases. This pressure can be used for various chemical and thermodynamic processes.
Q4. What role do gases play in photochemistry?
Ans. Gases are found in the atmosphere and hence, all its study is categorized under atmospheric chemistry. Photochemistry on the other hand is the use of light for various reactions which again happens in atmospheric conditions. So, gases aid in the photochemical reaction. For instance, chain reactions are observed with ozone and chlorofluorocarbons. In the ionosphere layer, gases usually convert into ions because of UV or cosmic radiation which are strong enough to remove electrons.
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