CHLOROFLUOROCARBONS AKA CFCS

By: Gajan Balakumar, Cindy Guo, Warren Viegas, Muhammad Bajwa, Komal Sandu & Sidarth Aiyar

AIMS OF THE RESEARCH To investigate the reduction of Ozone in the

stratospheric region of the atmosphere caused by the usage of Chlorofluorocarbons (CFCs).

Are CFCs guilty for the climate change during the late 20th century?

What lessons can be learned from our understanding of CFCs that can help us fight ozone depletion in the future?

What alternatives are there for this compound?

INTRODUCTION

THE MIRACLE CHEMICAL CFCs were once known as ‘Miracle’

Chemicals. First manufactured in the 1930s, and

industries soon found a wide variety of applications for them due to their chemical unreactivity and heat-absorbing properties.

Used as refrigerant’s in AC’s and other objects.

THE MIRACLE CHEMICAL CONT’D Are very handy in production since it

cost less and no real natural resources required for production

Organic bonding of Halo-Carbons, performed easily and efficiently in the labs.

Were given the household name “Freon’s”.

THEIR MISTAKE Scientists initially believed that CFCs would

be harmless in the earth's atmosphere because of their chemical inertness.

This and their lack of solubility in water, gives CFCs a long life span in the atmosphere (tens to hundreds of years)

However, in the stratospheric region of the atmosphere, these molecule break down, where the UV rays are intense.

THEIR MISTAKE CONT’D The break down releases

Chlorine which act as catalysts in the Ozone destruction (Reactions shown later on).

The ozone layer is important to humans and other life on earth because it absorbs harmful UV radiation (acting as a sort of UV "shield").

Long-term effects on humans' excessive UV exposure include skin cancer, eye damage (cataracts), and suppression of the immune system.

CHEMICAL REACTIONS

BACKGROUND INFO CFCs are completely manmade and produce

them for use in their machines. The main method used to make CFCs is to

take a methane or ethane based compound that has been chlorinated, i.e. has a chlorine attached to it, and react it with HF.

The process to make the various types of CFCs is the same. The reaction varies only slightly for each different type of CFC.

CHEMICAL FORMULAS Trichlorofluoromethane: CCl4 + HF →CFCl3 + HCl Dichloro-difluoromethane: CCl4 + 2HF →CF2Cl2

+ 2HCl Trichloro-trifluoroethane: C2Cl6 + 3HF →C2F3Cl3

+ 3HCl Dichloro-tetrafluoroethane:: C2Cl6 + 4HF →C2F4Cl2

+ 4HCl Chloro-pentafluoroethane: C2Cl6 + 3HF →C2F5Cl +

5HCl

BIOLOGICAL IMPACT

OZONE DEPLETION When CFCs reach stratosphere, dissolved by

UV light to release Chlorine atoms Chlorine atoms act as catalyst --> each atom

break down tens of thousands of ozone molecules before they exit stratosphere

CFCs take approximately 15 years to reach upper atmosphere from ground level and stay there for up to a century.

In 1973, chlorine found to be catalytic agent in ozone destruction

ACTION TAKEN March 1985, announced there was polar ozone

depletion over Antarctica --> initiatives to freeze or diminish production of CFCs

In 1980’s, 30-40% decrease in stratospheric ozone.

By spring of 1987, 50% ozone gone over antarctic continent

In space, there is TOMS (total ozone mapping spectrometer), which has shown downward trends in ozone layer at all latitudes near tropics.

GLOBAL WARMING Greatest global warming potential among gases

which induce global warming because they are persistent.

CFCs absorb infrared radiation Each CFC molecule absorbs tens of thousands as

much infrared radiation as Carbon Dioxide molecules CFC-11 is 3,000 - 12,000 as effective as carbon

dioxide CFC-12 is 7,000 - 15,000 as effective as carbon

dioxide

CFCS RAPIDLY ENTERED THE OZONE LAYER DURING THEIR USE

HUMAN IMPACT can lead to increase UVB light on

humans: immune inhibition cataracts --> major cause of blindness in

world, accounts for 50% of blindness (1994).

skin cancer

EFFECT ON PLANT 30-50% of all organisms affected by

UVB light --> therefore, change in UVB light can cause mutations to organisms

Increased UV may cause reduction in productivity of trees because it would affect their uptake of carbon dioxide from the atmosphere --> important because trees accounts for 80% of plant biomass productivity on earth.

ECONOMIC IMPLICATIONS

USES Coolants in

refrigeration and air conditioners

as solvents in cleaners for electronic circuit

boards blowing agents in the

production of foam (for example fire extinguishers)

propellants in aerosols.

PRODUCTION The total U.S. production of

chlorofluorocarbons was estimated to be 737 million pounds in 1975

Production of CFCs grew rapidly during the 20th century, growing from 42 kilo tonnes in 1950 to 1260 kilo tonnes in 1988

After their harmful effect on the ozone layer was discovered, production decreased to 147 kilo tonnes in 1999

PRODUCTION CONT’D A ban was imposed on the use of CFCs in aerosol-spray

dispensers in the late 1970s by the United States, Canada, and the Scandinavian countries.

In 1990, 93 nations agreed to end production of ozone-depleting chemicals by the end of the century.

In 1992 most of those same countries agreed to end their production of CFCs by 1996.

However, production of CFCs is still going strong in the developing world, particularly in South Asia, and Africa, as a result of economic constraints

Each year Americans dispose of roughly 13 million refrigerators and freezers and many of those contain chlorofluorocarbons (CFCs) that deplete the ozone layer and contribute to climate change

UN DECLARATION Their firm determination to take all

appropriate measures to phase-out the production and consumption of all fully halogenated chlorofluorocarbons controlled by the Montreal Protocol, as adjusted and amended, as soon as possible but not later than 1997.

London, 27-29 June 1990

THE UN’S SCHEDULE FOR REDUCTION OF CFC PRODUCTION

Concentration of CFCs in ozone layer has begun to level off

MAJOR ALTERNATIVES

FLUOROCARBONS, GLOBAL INDUSTRY AND ECONOMICS

Fluorocarbons are the CFC replacement for the majority of the producer and user industries.

Over US$25 billion has been invested in fluorocarbons to replace CFCs

Industry has played a vital role in developing alternatives as long as chlorine and bromine

emissions continue to decline, ozone levels in the stratosphere will return to normal by the middle of next century.

continued use of these fluorocarbons is actively encouraged to allow further progress in CFC replacement, especially in the developing world.

PHYSICAL PROPERTIES Fluorocarbons liquids are colorless. They have a high density due

to their high molecular mass, but less overall separation between F and C.

They comprise of Low and weak intermolecular forces; which gives it low viscosity when compared to liquids of similar boiling point for e.g. H2O.

They are immiscible with most organic solvents (ethanol and chloroform), but are miscible with hydrocarbons.

They have a very low solubility in water, and water has a very low solubility in FlouroCarbons.

The greater number of Carbon atoms, the increased amount of Boiling Point, density, viscosity etc. Except Gas solubility, all the physical properties have a positive correlation with the number of Carbons in FCs.

INDUSTRIES THAT RELY ON ALTERNATIVES

Air Conditioning Industry: millions of offices, public buildings, hospitals, hotels, and apartment buildings depend on HFCs to meet ambient temperature requirements. 

Food: The importance of refrigeration to the food manufacture, distribution and retail industries is fundamental: it plays a vital role in ensuring that food reaches consumers both fresh and fit to eat.

Aerospace & Electronic Industries: Previously dependent upon CFCs as solvents to achieve the very high levels of cleanliness required ensuring safe and consistent operation; these industries are now turning to HFCs and HCFCs. In fact, at present, they are often technically, environmentally and economically the best solutions.

INDUSTRIES THAT RELY ON ALTERNATIVES CONT’D Insulation: Fluorocarbon-blown foams provide better

insulation than other blowing agents being proposed, such as hydrocarbons or carbon dioxide.  Used in different applications, (e.g. building construction, refrigerated transport, heating pipes) foams blown with fluorocarbons conserve energy efficiently, providing environmental and economic benefits.

Medical: Due to their very low toxicity, a certain types of HFCs are developed as propellants replacing CFCs in metered dose inhalers (MDI) for asthmatics.  Dry powder inhalers are able to replace only a comparatively small fraction of the widespread MDI applications.

CONCLUSION "My findings do not agree with the climate models

that conventionally thought that greenhouse gases, mainly CO2, are the major culprits for the global warming seen in the late 20th century, Instead, the observed data show that CFCs conspiring with cosmic rays most likely caused both the Antarctic ozone hole and global warming. These findings are totally unexpected and striking, as I was focused on studying the mechanism for the formation of the ozone hole, rather than global warming.”- Qin- Bing Lu, professor of physics and astronomy at the University of Waterloo

CONCLUSION/ REFLECTION CFCs are one of the first examples of man made chemicals contributing

to the global warming and depleting ozone layer phenomena Through the collection of data, we were able to see that many “designer

chemicals” that have integrated themselves in society have moral, ethical, social, economic and environmental implications, that should be continued to be researched

Also, it is important to note when tackling such problems, the entire international community must be involved in one global initiative to decrease the use of CFCs, However differing economic, social and environmental situation must be accounted for

It is necessary for the scientific community to monitor and research how humanity’s applications of science affect the sustainability of the earth

Aside from developing alternatives, political action and global mandates are very effective in curbing the use of these chemicals, though are subject to change as time progresses

PERSONAL REFLECTION Our study of CFCs has led to conclude that there are

definitely ways to curb human dependence on ozone depleting chemicals, by researching as a team we looked into various perspectives on this issue, and believe maintaining the earth’s sustainability will always be a collective effort regardless of approach. The reduction of CFCs are regarded as a scientific as well as political triumph, showing how taking responsibility as global citizens is very important when pursuing scientific endeavours. However, the impacts of CFCs will still be felt well into the next century, and as we look to the future we must heed the lessons of CFCs to find ways to lessen our dependence on chemicals that harm the earth.

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