Chloroflourocarbons
Chloroflourocarbons were discovered in the 1920's by Thomas Midgley, an organic chemist at General Motors Corporation. He was looking for inert, non- toxic, non-flammable compounds with low boiling points that could be used as refrigerants. He found what he was looking for in the form of two compounds: dichlorodifluoromethane (CFC-12) and trichloromonoflouromethane (CFC-11). In both compounds, different amounts of chlorine and fluorine are combined with methane, which is a combination of carbon and hydrogen. These two CFCs were eventually manufactured by E.I. du Pont de Nemours and company, and, under the trade name “freon,” constituted 15% of the market for refrigerator gases.
CFCs were the perfect answer for cooling refrigerators and air conditioners. They were easily turned into liquid at room temperature with application of just a small amount of pressure, and they could easily then be turned back into gas. CFCs were completely inert and not poisonous to humans.
They became ideal solvents for industrial solutions and hospital sterilants.
Another use found for them was to blow liquid plastic into various kinds of foams. In the 1930's, household insecticides were bulky and hard to use, so CFCs were created because they could be kept in liquid form and in an only slightly pressurized can. Thus, in 1947, the spray can was born, selling millions of cans each year. Insecticides were only the first application for CFC spray cans.
They soon employed a number of products from deodorant to hair spray. In 1954,
188 million cans were sold in the U.S. alone, and four years later, the number jumped to 500 million. CFC filled cans were so popular that, by 1968, 2.3 billion spray cans were sold in America.
The hopes of a seemingly perfect refrigerant were diminished in the late
1960's when scientists studied the decomposition of CFCs in the atmosphere.
What they found was startling. Chlorine atoms are released as the CFCs decompose, thus destroying the Ozone (O3) atoms in the high stratosphere. It became clear that human usage of CF2Cl2 and CFCl3, and similar chemicals were causing a negative impact on the chemistry of the high altitude air.
When CFCs and other ozone-degrading chemicals are emitted, they mix with the atmosphere and eventually rise to the stratosphere. CFCs themselves do not actually effect the ozone, but their decay products do. After they photolyzed, the chlorine eventually ends up as “reservoir species” - they do not themselves react with ozone- such as Hydrogen Chloride, HCL, or Chlorine Nitrate, ClONO2.
These than further decompose into ozone hurting substances. The simplest is as follows: (How do CFCs Destroy the Ozone) Cl + O3 -----> ClO + O2 ClO + O
Life on this planet Earth is the product of a delicate balancing act provided by nature. Mankind's very existence is totally dependent on this fragile ecosystem's ability to maintain itself. A valuable player in the balance of the environment, the ozone layer, is facing a very serious threat by man. Chloroflourocarbons (CFCs), are chemical agents commonly found in refrigerants, aerosol sprays, and in the manufacturing of Styrofoam and industrial solvents. With the rate of more than a half-million tons of CFCs being spewed into the atmosphere yearly, the rate of ozone depletion is rising at an alarming rate. If a global effort is not made to end the unnecessary use of CFCs, the inhabitants of this planet face an extremely difficult and frightening future.
Two properties are required for fluid movement of Reservoir rocks and Source rocks: permeability and porosity. It consist voids or pores, ability to contain fluid (known as porosity) and the pores are interconnected (permeability) in order to allow flow to occur. Hydrocarbons can be termed as reservoir fluid. The volume of hydrocarbons stored in a reservoir depends upon the porosity of the reservoir rock. The rate and volume at which hydrocarbons are withdrawn depends upon the permeability of the reservoir rock. Almost complete pore space of the superior several kilometres of earth’s crust contains water. Therefore in this water environment hydrocarbons exist with amalgamation of oil, gas and water occurring in different proportions.
Stratospheric ozone absorbs 97-99% of ultraviolet radiation. As this protective layer continues to dissentigrate, human health will suffer. One American dies every hour from skin cancer, a direct result of ozone depletion by anthropogenic chemicals, primarily CFCs, which damage the ozone layer. Alternate chemicals are now being used in the place of CFCs that will not damage statospheric ozone, and there is international recognition of the importance of developing these chemicals. The Montreal Protocol is an international treaty which limits the production of ozone depleting substances. Still, human health is at risk from the deletion of ozone, and the risk factor will continue to rise unless people and industries become more aware of the implications connected with everyday use of chemicals which destroy stratospheric ozone.
While doing his research Molina learned that these compounds move up to the ozone and stay there. He expected the compounds to be destroy by the solar radiation. However to his surprise he formed that chlorofluorocarbons would simplify into component element when exposed to radiation. This simplify components produce a highly concentration of pure chlorine atoms. From there he already knew that the ozone layer can be destroy with chlorine.
The endocrine system of animals is a main source of bioregulatory compounds. Hormonal actions regulate all aspects of animal life: reproduction and development, digestion, metabolism, behavioural responses etc. (Hertenstein 2006, Norris 2007). Hormones and glands of vertebrate and invertebrate endocrine system differ in structure and function, but their main regulatory role remains conserved. However, the balance among the environmental clues, hormonal signals and organisms’ responses can be easily disturbed. One of the causes of this disturbance is the presence of Endocrine Disrupting Chemicals (EDC’s) in the environment.
Rowland and Mario Molina proposed that CFC emissions would lead to the destruction of the stratospheric ozone layer2. At that time Drs. Rowland and Molina suggested that
1,1-dichloroethane is listed by the Environmental Protection Agency (EPA) as one of the Halogenated Organic Compound (HOC)s that needed to be regulated by the government under the category of C “Possible Human Carcinogen”. HOCs are defined by EPA as any compounds having a carbon-halogen bond (“40 CFR Part 268, Appendix III to Part 268 - List of Halogenated Organic Compounds Regulated Under § 268.32,” n.d.) It is flammable oily liquid, without color, but has a very delicate odor that resembles chloroform. Apart from being an intermediate product of other industrial chemicals and/or being used in the production processes of plastic wrap, adhesives and synthetic fiber, we may come across it in the form of common household products such as degreaser,
6CO2 + 12H2O + sunlight ---> 6O 2 + C6 H12O 6 + 6H2 O
O3. Ozone is formed when oxygen in the air is subjected to an electrical discharge, such
The earth cannot hold life without the ozone, which epitomizes the very opposite of a trivial situation. In the ozone cycle, there are three forms of oxygen present: atomic oxygen, O, molecular oxygen, O2 (oxygen gas) and triatomic oxygen, O3. Photodissociation of the oxygen molecule converts molecular oxygen into two atomic oxygen radicals, which then combine with more O2 molecules to form O3 molecules. These O3 molecules absorbs UV rays thus preventing the risk of cance...
15.2) The accumulation of chlorofluorocarbons is responsible for depleting the atmospheric zone. The atmospheric zone has changed in concentration due to human activity. The CFCs release chlorine atoms which react with ozone reducing it to molecular O₂. Following chemical reactions release the chlorine which reacts with other ozone molecules in a catalytic chain reaction. The ozone layer is getting thinner and thinner as stable air at places such as Antarctica allows reaction to continue. The accumulation of CFCs has led to increased UV radiation in sunlight reaching the earth thereby decreasing ozone levels. The global temperature has increased.
As the twenty-first century progresses, it has become increasingly apparent just how many challenges the world faces. Prominent among these concerns are environmental issues, in particular, ozone depletion and climate change. While the international community has been exceptionally successful in its struggle to reduce the production and consumption of chlorofluorocarbons (CFCs), the organic compounds that contribute to the ozone issue, its efforts to tackle climate change have yielded considerably fewer advancements. A number of factors that helped the proceedings of the ozone regime, or campaign, are not applicable to the climate change regime. The issue of limiting CFCs was much less politically and economically charged than that of reducing greenhouse gases (GHGs), which cause the greenhouse effect and the consequent warming of the planet. Climate change has been referred to as the ultimate “tragedy of the commons”, an important metaphor in economics that helps explain why this subject is still at the centre of much heated debate and has yet to be resolved in a manner similar to that of the ozone problem.
Since the days of Aristotle, all substances have been classified into one of three physical states. A substance having a fixed volume and shape is a solid. A substance, which has a fixed volume but not a fixed shape, is a liquid; liquids assume the shape of their container but do not necessarily fill it. A substance having neither a fixed shape nor a fixed volume is a gas; gases assume both the shape and the volume of their container. The structures of gases, and their behavior, are simpler than the structures and behavior of the two condensed phases, the solids and the liquids
Los Clorofluorocarbonados (CFC) y sus derivados tienen como fuentes principales algunos productos industriales, y los óxidos de nitrógeno, que se producen por multitud de causas, principalmente por la quema de combustibles fósiles y la utilización de fertilizantes químicos.
Hydrocarbons are compounds formed by carbon and hydrogen atoms. They are used as fuels to produce energy in incomplete and complete combustion reactions. Incomplete combustion occurs when hydrocarbons react with a small amount of oxygen (O2), whilst complete combustion occurs when hydrocarbons react with large amounts of oxygen. Incomplete combustions produce water (H2O), carbon monoxide (CO) and/or soot (C). The CO and soot produced from incomplete combustion can have harmful consequences on humans and the environment. They not only damage human health, but also contribute to the current issue of global warming, ozone formation, and black carbon footprint. That being said, CO is vital to the human body in order to properly function.