Ozon

Denne artikel omhandler luftarten ozon. For den moldoviske musikgruppe, se O-Zone.

Ozon er en luftart (O₃) i stratosfæren, der beskytter mod ultraviolet stråling. Industrielt bruges ozon som en kraftig oxidator. Ozon er kemisk ustabilt, og tilstedeværelsen af selv forsvindende mængder af "fremmedstoffer" gør det yderst eksplosionsfarligt. Af den grund bruges ozon ikke som iltningsmiddel i raketters motorsystemer, til trods for at ozon er mere kompakt end en tilsvarende mængde "normal", molekylær ilt (O₂).

Ozon kan dannes ved en spontan reaktion mellem svovlilte (SO₂) og forskellige kvælstofilter (NO_x). Da disse luftarter oftest findes, hvor man har røg fra kraftværker, fabriksskorstene m.m. i blanding med udstødningsgas fra biler, vil der dannes ozon i tæt trafikerede områder af vore byer. Ozonens ustabilitet fører til, at der dannes frie iltatomer (O), som er yderst aggressive over for levende væv. Det kan f.eks. ses af de talrige ozonskader på bytræer og -buske (skaden ligner "blancherede" pletter). På den måde kan ozonskader bruges som indikator for, at der er svovlilte og kvælstofilte i luften.

I laboratoriet kan ozon producers ved elektrolyse, af 3 molær svovlsyre som elektrolyt, med en katode af grafit og en anode af platintråd.
Reaktionen der sker, ser således ud:

3 H₂O → O₃ + 6 H+ + 6 e− ΔEo = − 1.53 V
6 H+ + 6 e− → 3 H₂ ΔEo = 0 V
2 H₂O → O₂ + 4 H+ + 4 e− ΔEo = −1. 23 V

Ozons ætsende virkning på levende væv har tidligere været udnyttet lægeligt ved, at man lagde tuberkulosesanatorier i tætte nåleskove. Der dannes nemlig en smule ozon, hvor der vokser nåletræer, og ved indånding fik man dræbt tuberkulosebakterierne dybt nede i patienternes lunger.

Ozon er en aggressiv oxidant, og i større mængder vil den mærkbart angribe slimhinder (f.eks. lunger). ^[1] ^[2]

Se også

Eksterne links

Kilder/referencer

^ rhtubs.com: The Dangers of Indoor Ozone Arkiveret 23. august 2011 hos Wayback Machine Citat: "...The American Academy of Allergy, Asthma and Immunology (AAAAI) has concerns that high ozone levels result in the detrimental affects on the respiratory system including...There have been experiments in which a mouse was killed in 45 minutes at about a 100 PPM concentration of ozone...One other down side to ozone is it's corrosiveness to certain plastics, most notably plastics used for electrical wire insulation and printed circuit boards..."
^ greenfacts.org: 2 How does Ozone (O3) affect human health? Citat: "...Short-term exposure to ozone peaks can temporarily affect the lungs, the respiratory tract, and the eyes...2.5 No exposure threshold has been identified below which nobody’s health is affected by ozone exposure. This is because different individuals respond very differently to ozone exposure. A threshold has been determined for lung damage and inflammation, but studies on this topic have generally not tested especially sensitive subjects...."

[1] rhtubs.com: The Dangers of Indoor Ozone Arkiveret 23. august 2011 hos Wayback Machine Citat: "...The American Academy of Allergy, Asthma and Immunology (AAAAI) has concerns that high ozone levels result in the detrimental affects on the respiratory system including...There have been experiments in which a mouse was killed in 45 minutes at about a 100 PPM concentration of ozone...One other down side to ozone is it's corrosiveness to certain plastics, most notably plastics used for electrical wire insulation and printed circuit boards..."

[2] reenfacts.org: 2 How does Ozone (O3) affect human health? Citat: "...Short-term exposure to ozone peaks can temporarily affect the lungs, the respiratory tract, and the eyes...2.5 No exposure threshold has been identified below which nobody’s health is affected by ozone exposure. This is because different individuals respond very differently to ozone exposure. A threshold has been determined for lung damage and inflammation, but studies on this topic have generally not tested especially sensitive subjects...."

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