Air mixtures

Air is a mixture of gases - 78% nitrogen and 21% oxygen - with traces of water vapor, carbon dioxide, argon, and various other components

Other components in air

•Sulfur dioxide - SO2 - 1.0 parts/million (ppm)•Methane - CH4 - 2.0 parts/million (ppm)

•Nitrous oxide - N2O - 0.5 parts/million (ppm)•Ozone - O3 - 0 to 0.07 parts/million (ppm)•Nitrogen dioxide - NO2 - 0.02 parts/million

(ppm)•Iodine - I2 - 0.01 parts/million (ppm)

•Carbon monoxide - CO - 0 to trace (ppm)•Ammonia - NH3 - 0 to trace (ppm)

GASES OF THE AIRThe air around us is a mixture of gases, mainly nitrogen and oxygen, but containing much smaller

amounts of water vapor, argon, and carbon dioxide, and very small amounts of other gases. Air also contains

suspended dust, spores, and bacteria. Because of the action of wind, the percent composition of air varies only

slightly with altitude and location. The table indicates the composition of a typical sample of air after all water

vapor and suspended particles have been removed.

The amount of water in the air varies tremendously with

location, temperature, and time. In deserts and at low temperatures

the content of water vapor can be less than 0.1% by volume. In

warm, humid zones, the air may contain over 6% water vapor.

Air is the commercial source for many of the gases it contains.

It is separated into its components by fractional distillation of

liquefied air. Before air is liquefied, water vapor and carbon dioxide

are removed, because these substances solidify when cooled

and would clog the pipes of the air liquefaction plant. The dry,

nitrogen and about 1.25% noble (or “inert”) gases, argon, neon, krypton, and xenon. Nitrogen is second only to

sulfuric acid in the volume produced by the U.S. chemical industry. Its major uses are as an inert blanketing

atmosphere in chemical processing (14%), electronics (15%), and, in liquid form, as a freezing agent (21%).

Nitrogen is used to make agricultural fertilizers, such as ammonia and nitrates. It is also used in the production

of acrylonitrile, CH2=CHCN, which is important in the manufacture of synthetic fibers such as Orlon, and in the

production of cyanamide, HN=C=NH, which is polymerized to Melamine plastic. Because it is a very poor

oxidizing agent, nitrogen is used to pack oxidizable foods, such as ground coffee, and as an inert atmosphere in

the manufacture of electronic components. Liquefied nitrogen, because it is very cold, is used extensively to chill

materials for preservation, as in freeze-drying of foods, and in manufacturing processes that require low temperatures,

such as machining of aluminum.

CO2-free air is compressed to about 200 atmospheres. This compression

causes the air to become warm, and the heat is removed

by passing the compressed air through radiators. The cooled, compressed

air is then allowed to expand rapidly. The rapid expansion

causes the air to become cold, so cold that some of it condenses.

By the alternate compressing and expanding of air, most of it can

be liquefied.

Nitrogen is obtained from liquid air by distillation at

-196EC. The gas obtained by this process is actually a mixture of

Common Pressure Units frequently used as alternative to "one Atmosphere"

•76 Centimeters (760 mm) of Mercury

•29.921 Inches of Mercury

•10.332 Meters of Water

•406.78 Inches of Water

•33.899 Feet of Water

•14.696 Pound-Force per Square Inch

•2116.2 Pounds-Force per Square Foot

•1.033 Kilograms-Force per Square Centimeter

•101.33 Kilopascal

Air ScrubberScrubber systems are a diverse group of air pollution control devices that can be used to

remove some particulates and/or gases from industrial exhaust streams. The first air scrubber was designed to remove carbon dioxide from the air of an early submarine, the

Ictineo I, a role which they continue to be used for to this day. Traditionally, the term "scrubber" has referred to pollution control devices that use liquid to wash unwanted

pollutants from a gas stream. Recently, the term is also used to describe systems that inject a dry reagent or slurry into a dirty exhaust stream to "wash out" acid gases. Scrubbers are

one of the primary devices that control gaseous emissions, especially acid gases. Scrubbers can also be used for heat recovery from hot gases by flue-gas condensation.

Wet scrubbing

The exhaust gases of combustion may contain substances considered harmful to the environment, and the scrubber may remove or neutralize

those. A wet scrubber is used to clean air, fuel gas or other gases of various pollutants and dust particles. Wet scrubbing works via the

contact of target compounds or particulate matter with the scrubbing solution. Solutions may simply be water (for dust) or solutions of

reagents that specifically target certain compounds.

Process exhaust gas can also contain water soluble toxic and/or corrosive gases like hydrochloric acid (HCl) or ammonia (NH3). These

can be removed very well by a wet scrubber.

Dry scrubbingA dry or semi-dry scrubbing system, unlike the wet scrubber, does not saturate the flue gas

stream that is being treated with moisture. In some cases no moisture is added, while in others only the amount of moisture that can be evaporated in the flue gas without

condensing is added. Therefore, dry scrubbers generally do not have a stack steam plume or wastewater handling/disposal requirements. Dry scrubbing systems are used to remove

acid gases (such as SO2 and HCl) primarily from combustion sources.

There are a number of dry type scrubbing system designs. However, all consist of two main sections or devices: a device to introduce the acid gas sorbent material into the gas stream

and a particulate matter control device to remove reaction products, excess sorbent material as well as any particulate matter already in the flue gas.

Dry scrubbing systems can be categorized as dry sorbent injectors (DSIs) or as spray dryer absorbers (SDAs). Spray dryer absorbers are also called semi-dry scrubbers or spray

dryers.

Bacteria spread

Poorly maintained scrubbers have the potential to spread disease-causing bacteria. The problem is a result of inadequate cleaning. For example, the cause of a 2005 outbreak of Legionnaires' disease in Norway was just a few infected scrubbers. The outbreak caused

10 deaths and more than 50 cases of infection.

The Importance Of AirOther planets have sunlight, but the Earth is the only planet we know that has air and

water. Without air and water, the Earth would be unable to sustain life.

A diverse community of plant and animal life has thrived on this planet for millions of years, sustained by the sun and supported by the soil, water and air.

Definition of air pollutionAir pollution occurs when the air contains gases, dust, fumes or odour in harmful amounts. That is, amounts which could be harmful to the health or comfort of humans and animals or

which could cause damage to plants and materials.

The substances that cause air pollution are called pollutants. Pollutants that are pumped into our atmosphere and directly pollute the air are called primary pollutants. Primary

pollutant examples include carbon monoxide from car exhausts and sulfur dioxide from the combustion of coal.

Further pollution can arise if primary pollutants in the atmosphere undergo chemical reactions. The resulting compounds are called secondary pollutants. Photochemical smog is

an example of this.

pollutantsAir pollutants mainly occur as a result of gaseous discharges from industry and motor

vehicles. There are also natural sources such as wind-blown dust and smoke from fires.

Some forms of air pollution create global problems, such as upper atmosphere ozone depletion and global warming. These problems are very complex, and require international

cooperative efforts to find solutions.

Gases that causes suffocation

An asphyxiant gas is a nontoxic or minimally toxic gas which reduces or displaces the normal oxygen concentration in breathing air. Breathing of oxygen-depleted air can lead to

death by asphyxiation (suffocation). Because asphyxiant gases are relatively inert and odorless, their presence in high concentration may not be noticed, except in the case of

carbon dioxide (hypercapnia).

Toxic gases, by contrast, cause death by other mechanisms, such as competing with oxygen on the cellular level (e.g., carbon monoxide) or directly damaging the respiratory system

(e.g., phosgene). Far smaller quantities of these are deadly.

Notable examples of asphyxiant gases are nitrogen, argon, and helium. Along with trace gases such as carbon dioxide and ozone, these comprise 79% of Earth's atmosphere. The

atmosphere is mostly harmless because the remaining 21% is O2.

Asphyxia hazardAsphyxiant gases in the breathing air are normally not hazardous. Only where elevated concentrations of

asphyxiant gases displace the normal oxygen concentration a hazard exists. Examples are:

Environmental gas displacement

Confined spaces, combined with accidental gas leaks, such as mines, submarines,refrigerators, or other confined spaces

Fire extinguisher systems that flood spaces with inert gases, such as computer data centers and sealed vaults

Large-scale natural release of gas, such as during the Lake Nyos disaster in which volcanically-released carbon dioxide killed 1,800 people.

Release of helium boiled off by the energy released in a magnet quench such as the Large Hadron Collider or a magnetic resonance imaging machine.

Climbing inside an inflatable balloon filled with helium

Direct administration of gas

Exclusive administration, such as inhaling the contents of a balloon filled with helium

Inadvertent administration of asphyxiant gas in respirators

Use in suicide and erotic asphyxiation

By : THE

STUDENT OF THE

DOON GLOBAL

SCHOOLADITI SHARMA

GRADE :8 “A”

THANK YOU