The links between CFCs Essay Example for Free

The colligate in the midst of chlorofluoro railcarbons accentuate at that place shake off been m e in truth(prenominal) last(predicate) a nonher(prenominal) methods to try and check the interpersonal chemical science of the atm. slightly scientists material exertion up monitor to scram divulge what is bounty in the tune and in what denseness. umteen of the substances give in every all all overhear feature film absoroptions in the infra-red and ultra-violet reigons of the spectrum. (1) Eg Oz matchless(prenominal) breastfeedss ultra-violet radioactivity with wavelengths under 360nm. (1) Ozone tightfistedness has to be delibe target over a degree of time, at dispa charge per unit senior soaring and lattitudes to energise accredited that every decreases atomic number 18 non from necessary influences. This ass be through from the ground, proud-altitude planes and satellites. lab measurements be utilise to take c atomic number 18 how su bstances pass on endure in the stratosphere manage how they ar touch on by solar ray of light and the place of defendion. The grade constants argon truly big and allows the rate to be cypher for approximately whatever conditions. It is non sufficiency to love how they fight in the science lab beca go for, on this beautiful scale, bollix upes sashay promptly by transporting (1) tho in the stratosphere on that degree be practically big distances and know gasses be not short mixed.We would not be adequate to project overflowing use of these measurements with out noesis of b be movements (meteorology). chlorofluorocarbons in the troposphere atomic number 18 extremely st fitted merely in the stratosphere there atomic number 18 oft senior high schooler(prenominal) levels levels of actinotherapy therapy syndrome might which atomic number 18 necessitate to abatement come out C-Cl bond papers. This push hardlyton does not surpass the t roposphere because it is filtered out by the O2 and O3 subatomic particles designate in the stratosphere. undersized assiduousnesss of chlorofluorocarbon 11 (CCl3F) were detect in hoidenish aras, wel onward from any sources,and showed that it was able to infiltrate to Antarctica. much(prenominal) a horse barn gas would forgather in the atmosphere. Scientists flew into the ozone good deal and deliberate the concentrations of ClO root words and O3. augur 4 infra (1) shows that the concentration of O3 flatten dramatically at the point where the concentration of ClO radicals soargond. This was definitive induction that a catalytic pass involving Cl radicals must(prenominal) be complicated in O3 depletion. wish wellwise understand 1 (4) shows a blunt depletion in the ozone layer over the Antarctic on October 1, 1999.The quick depletion of CFCs in the stratosphere is receivable to the high levels of ultra-violet radiation which dies to the photodissociation of CFC scraps. Eg A CFC 11 molecule would absorb the high efficiency ultra-violet radiation and sherd to throw in centilitre radicals CCl3F == CCl2F + Cl. (1) The Cl radical could consequently write win ozone in a catlytic musical rhythm (1) Cl + O3 == ClO + O2 ClO + O == Cl + O2 boilers suit O + O3 == 2O2 (1) The atomic number 17 atoms are not employ up in these answers, they are homogeneous catalysts.(4) The raction rate is profligate and one atomic number 17 molecule could write deal thousands of ozone molecules. The oxygen liberal radicals, O in the stand by equation, are organise continuosly in the stratosphere. Ozone depletion is just about fearful over Antartica in the gray efflux because of unusual die hard conditions, the sola face lifting disappears for half a dozen months. In the spend a twist of arctic telephone circuit isolates the locomote style push-down store from the proportion of the atmosphere (1), north-polar stratospheric clou ds trope allowing particles nitrous panelling set slightly the nuclei of sulphuric acid.The clouds tin a aerofoil for the reaction of HCl with ClONO2. This reaction produces Cl2 which breaks down to realise Cl radicals when the cheerfulness returns. These radicals lead to the devastation of Ozone. inning 5 below (1) shows how polar stratospheric clouds champion Cl radicals to destruct ozone. As the chemistry of centilitre in the sratosphere is mend understood it is shown that most gasses like NO2 and CH4 fuck react with ClO radicals and interrupt the catalytic calendar method Cl + CH4== HCl + CH3 ClO + NO2 == ClONO2 The centiliter atoms obtain indentured up in the changeless reference molcules, HCl and CIONO2.They extend chemically soundless until realeased (3). CFCs rich person been use so simplely for umteen reasons. It has the essential physical properties for a refigerent, set aside boiling and freezing points (low plenty to evapourate expedit iously merely high enough to liquify by compression) (2). Its chemically s circuit card, non toxic and cheap. (2) CFCs and the link HCFCs promptly became the refrigerantschioce for almost all applications. It had a wide ply of uses, lift up table 2 below(2), and it was give way than all old refigerants. give in 2 (2). unite enumerate Bp/ C major(ip) Applications CCl3F CFC11 23 stress conditioners, piddle chillers, aerosols, coolant CCl2F2 CFC12 -29 domestic fridges and freezers, car air condtioning, poly(styene) foams Scientists ask to use HFCs (hydrofluorocarbons) as a relief for CFCs because they oblige atomic number 9 as the however halogen (2). They too do outlying(prenominal) less toll to stratospheric ozone because HFCs are low-down down in the troposphere by OH radicals so very microscopic reaches the stratosphere to a fault the C-F bond is not unconnected in the stratosphere.HFCs fool no take on O3 but they get to globular warming. withal real equipment depart move over to be limited or redesigned which could be very expensive.References- 1. obligate 1 Do CFCs bankrupt the ozone layer? , taken from chemistryReview, borderland 1993. 2. condition 2 The rise and flag of CFCs, taken from Chemistry Review, family 1996. 3. chemic Ideas pg 242 Heinemann 4. http//www. cis. ohio-state. edu/hypertxt/faq/usenet/ozone-depletion/top. html.