Gases are the volatile form of matter present on the earth.
They can be converted to liquids and even solids by cooling.
Gases are the prime reason for existence of life on earth.
Oxygen is a gas which helps in production of energy for the body.
While carbon dioxide is helpful in formation of food by photosynthesis.
Similarly nitrogen from air is converted into ammonia which acts as manure to plants in soil.
These gases are of different types like natural ones, artificial and even manufactured ones. But they vary in chemistry, properties and uses.
Types of gases
There are two types
a) Natural gases (most common gases)
b) Artificial gases.
The natural gases are those which are formed and present in nature. They are most common gases which are easily available through air. While the artificial gases are made by man from chemical reactions.
The natural gases are again of two types as
- Elemental gases: These are the gases formed along with matter on earth and other planets. These gases are made of single element atoms. Examples of gases include Hydrogen (H2), oxygen (O2), nitrogen (N2), noble gases are the gases in the atmosphere.While Chlorine (Cl2), Fluorine (F2) are present in combination substances.
- Compound gases: These are also gases formed in nature out of biological processes. These are chemically made of two or more elements. They are formed by combination of carbon, oxygen, nitrogen, hydrogen, nitrogen. Ex: carbon-dioxide (CO2), methane (CH4), sulfur dioxide (SO2), ammonia (NH3) etc.
These gases are present even before life existed on earth. So they are not harmful to nature as long as their concentration in the air ratio’s are not disturbed a lot.
The artificial gases are those which are synthesized by chemical reactions. They are made of many elements besides those listed above.
These artificial gases include chlorofloro carbons, anesthetics, sterilizing agents etc. They are made by industrial processes for our use.
These are meant for special needs of man but are not useful to nature. In turn some of them are harmful to the nature. Cholorofloro carbons used in refrigerators cause harm to the ozone layer. This ozone layer protects us from the harmful UV rays of the sun rays from reaching the ground. Hence their use in refrigerators are discontinued.
Also there are acidic gases ex: Hydrochloric acid (HCl), Hydrofloric acid (HF). Since they are volatile, they are used as mixture in water. They have very low pH like 1.
Basic gases are those which have pH more than 7. Ex: Ammonia (NH3).
Thus we can understand that these gases are useful and also can be harmful to man.
Uses of Gases
There are many uses of gases. Before we go deeper lets see the
list of common gases and their uses.
|Oxygen||Respiratory support, Welding, Sterilzer|
|Carbon Dioxide||Refrigerant, Anti-explosive in combination with other gases,|
|Nitrogen||Liquid nitrogen for cold storage, For oxygen free environment, In respiratory support in health care.|
|Neon, Argon, Xenon||In electric bulbs and tubes|
|N2O (nitrous oxide)||Anesthetic in dental surgery|
|Sulfur dioxide||To preserve fruits, Wine making|
In medicine: Gases are used in healthcare for respiration and anesthesia.
To aid respiration: In case of respiratory insufficiency. This is a condition of lungs where they are unable to expand and contract. In being so they cant take sufficient oxygen from air spontaneously. This is seen in diseases like COPD and respiratory insufficiency diseases. Here oxygen in combination with normal air, nitrogen or even carbon dioxide is used to aid proper respiration. This helps to recover from asphyxia in case of old age people and also those with brain and spinal cord damage.
Also in tissue culture procedures, where tissue or cell is grown outside the body gases are supplied. For this especially oxygen in combination with nitrogen is suitable.
For anesthesia: Gases like halothane, enflurane, ether, chloroform are used to make the person loose consciousness. This is especially important during operations, surgery and even c-section delivery. The specialty in their use is, due to being gases, they are easily inhaled by breath. The onset of anesthesia is very fast and even the recovery is fast as the gas molecules can also be exhaled by breath. Since the induction and recovery is fast, these gaseous anesthetics are used even for maintenance of anesthesia.
For chemical analysis: Gases are also used in analysis of compounds and substances in drug manufacture, nutrition and research. Gases like nitrogen are used in gas chromatography. While in flame photometry gases like hydrogen, argon are used. These gases are used because they aid in transfer of the compounds and also their ability to ignite.
Also gases like oxygen, acetylene are used in metal welding, called gas welding.
Even for automobiles, there is research going on for use of hydrogen as fuel.
Similarly, Methane a biomolecule obtained from biomass is used to generate electricity.
For lights & lamps: Most of the lamps made have noble gases. The gases helium, xenon are commonly used in the lamp helps to prevent damage to the electrodes in the bulb due to high velocity ions. These ions slow down the velocity of ions and there by enhance the lifespan of filament in the tubes. and bulbs.
For refrigerator (cooling): Gases like carbon dioxide, ammonia, chloroflorocarbons, sulfur dioxide are used for cooling the systems. These gases take the heat from within and release it out by condensing to liquid. They then convert to gas by taking the internal heat. Thus they convert from liquid phase to gas phases alternatively. This way they can aid in cooling of the compartments in a fridge and also in air conditioners. They are used widely in storage, pharmaceutical industries, cars and other automobiles.
For Cold transport: When some thermo sensitive substance have be transferred solid or liquid gases are used. Liquid nitrogen and solid carbon-dioxide have very low temperatures suitable to keep the substances in frozen state in a pack. Hence these are widely used in transfer of food stuff, tissue samples and useful microbes. Liquid nitrogen has a temperature of -196° celcius, while solid carbon dioxide has a temperature of -78.5° celcius.
For sterilization: Gases like ethylene oxide are used for sterilization. They are toxic and also highly inflammable. So it is used in combination with carbon-dioxide to prevent explosion. They aid in killing of microbes and keeping the area sterile. This is specially useful in drug, food carrying containers. Once the drug or food packets are sealed, they are transferred into containers for transport. Once the containers are packed with drug or food packs, these toxic gases are allowed to pass through. These gases inside move into every corner of the container even in between gaps and helps in effective sterilization.
In Research: Gases are also used in research for experimental purposes. Nitrogen is used to create a non-oxygen atmosphere. Also it is used to remove oxygen from solutions to study oxidation levels. In plant tissue culture, to provide sterile oxygen supply to the growing plant tissue.
For purification of substances: When a solid or liquid is impure, it can purified by converting it into gas and then reconverting to the prior form. Even some of the solids like naphthalene can be purified by sublimation process. If the material is heat sensitive, it can be boiled in low temperature under vacuum to convert into gas and then the gas is re condensed to original state of solid or liquid. Thus converting a substance into gas helps in its purification.
Similarly in swimming pools and public water supplies, bleaching powder is used to kill diseases causing microbes. This bleaching powder i.e. Ca (ClO)2 is a strong oxidizer. When mixed in water, it releases chlorine and oxygen gas atoms (O) which are highly toxic to microbes. These gas atoms kill the microbes and hence sanitize fresh water.
Also volatile forms of gases are used as room freshers, insect repellents etc.