cfc's mona presentation

8/7/2019 CFC's mona presentation

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Presented byRani Mehmoona Sadia

MS-IRoll No:- 14

Lahore College For Women University


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What Are CFCs?CFCs is short forChlorofluorocarbons.

Commercially they are wellknown as Freons.

They are chemicals thatwere widely used by

factories (because they areeasy to store and cheap toproduce).


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Chlorofluorocarbons are

simple organiccompounds where all of

the hydrogen atoms have

been replaced with the

halogens chlorine and

fluorine (e.g. CFC-11

CFCl3 and CFC-12 CF2Cl2).


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j As solvents in Electronic industry

j In Fire extinguishers

j As dry cleaning

solvents


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Use of CFC's. Information from the US Environmental Protection Agency.


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Consequences of using CFCs

Effect on Ozone layer:-CFCs release chlorinemolecules which attackand destroy the ozonelayer and can cause ozoneholes.

Ozone holes appearedabove both the North andSouth poles and they wereincreasing in size.


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The destruction of stratospheric ozone


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Effect on Global warming

In the last 150 years, global temperatures havebeen rising and the amount of carbon dioxide inthe atmosphere has reached phenomenal levels.

The ozone layer over the Polar regions has

depleted to alarmingly low levels since the 1950s.Studies conducted by NASA have shown thatozone depletion over the Antarctic and Arcticregions will be at its worst between 2010 and2019.

Ice cover in theArctic sea hasdecreased

dramaticallydue to risingglobaltemperatures.

20051979


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Causes of global warmingCauses of global warming

Increase in greenhouse

gas emission

Due to human

activities

Sources of carbon

dioxide: Burningfossil fuels in cars,

factories and

power plants

Sources of nitrous

oxides: Vehicle

exhaust pipes,

fertilisers, livestockwastes

y Sources of CFCs: Aerosol cans,

air-conditioners, refrigerators,

plastic forms

Sources of methane:

Landfills, rice

paddies, guts of

cattle


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Greenhouse gases are gases inthe atmosphere which trap heat

from the Suns rays. Examples ofgreenhouse gases are carbondioxide, methane, nitrous oxidesand chlorofluorocarbons (CFCs).

Lu argues that the

correlation betweenglobal temperatureand CFCs is evidence

that CFCs have beenthe dominant driver of

climate over the pastcentury


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Effects on Human health

Causes the skin cancer

Melanoma, Nonmelanoma Skin Cancers,Basal Cell Carcinomas , Squamous CellCarcinomas


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Cataracts and Pterygium

Immune Suppression


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hydrochloroflourocarbons

hydroflourocarbons hydrocarbons

ammonia

helium terpenes

water and steam


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HydrochloroflourocarbonsHCFCs

break down faster (2-20years)

pose about 90% less danger to ozone layer

can be used in aerosol spray

also can be used inairconditioning

refrigeration

foam

cleaning agents


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Disadvantages are greenhouse gases

still deplete ozone when used in large quantities

health effects are largely unknown

expensive

may lower energy efficiency of appliances can be degraded to triflouroacetate(TFA)

can inhibit plant growth in wetlands


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Hydroflourocarbons Break down faster (2-20 years)

do not contain ozone destroying chlorine

can be used in

aerosol spraysrefrigeration

air conditioninginsulating foams


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Disadvantages

Are potent greenhouse gases

Expensive

Safety question about flammability and toxicity still

unresolvrd Can be degraded to TFA, which can inhibit plant growthin wetlands

May lower energy efficiency of appliances

Production of HFC-134a, a refrigerant substitute, yieldsan equal amount of methyl chloroform, a serious ozonedepleter


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HYDROCARBONS (HCS)

Such as propane and butaneCheap and readily available

Can be used in

aerosol sprays

refrigerationfoam

cleaning agents

Not patentable

Can be made locally in developing

countries


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disadvantages can be flammable and

poisonous some increase in groundlevel air pollution


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Ozone depletion potentials


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Ammonia

Simple alternative for refrigerators

Widely used before CFCs

the only honest refrigerant

Ammonia is an environmentally compatible refrigerant

because it has an ozone depletion potential (ODP) ofzero and a global warming potential (GWP) of zero. Noother refrigerant can claim such perfect statistics.


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Because of its superior thermodynamic

properties, ammonia as a refrigerantrequires less energy to produce a givenamount of cooling than otherrefrigerants.

Ammonia Safety

Ammonia refrigeration has a excellent safety record and in

spite of being by far the most widely used refrigerant on theplanet, lags behind other common refrigerants such as R22 inaccident statistics.


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This is in part due to its sharp and pungent odour which

warns of its presence even at very low concentrations, andencourages people to leave the area before any dangerexists. No other refrigerant possesses such an effective self-alarming

effect. isadvantages Toxic if inhaled

Flammable

Must be handled carefully Ammonia is hazardous at high concentrations


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Effects on human health


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Helium

D Effective coolant for

Freezers

Refrigerators

Air conditioners

In fusion power

plants

D Helium is the most favored

coolant due to its low tendency

to absorb neutrons and

become radioactive


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Disadvantages

This rare gas may become scarceif use is widespread, but verylittle coolant is needed perappliance


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Terpenes

From the rinds of lemons andother citrus fruits

Effective for cleaning electronic

parts Terpene-based formulations have been shown to bethe only viable substitutes for chlorofluorocarbons(CFCs)

Terpene-based cleaners are safe for employees and the

environment, they are effective for conventional andsurface-mount technology, and they are cost competitivewith CFCs


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Water & Steam

Effective for some cleaning operations and forsterilizing medical instrument

Disadvantages

Creates polluted water that must be treated

Wastes water unless the used water is cleaned upand reused.


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Current situation

Due to a lot of human efforts forthe past decade,inspite increasedpollution,use of CFCs has been

greatly reduced and has beensubstituted with other lessharmful compounds.

Its on us to make our

envoirnment live worthy for usbefore we have to pay the price.


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Save earth


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cfc's mona presentation

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