Term
| What is the formula of ozone? |
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Definition
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Term
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Definition
| A pale bluish gas with a pungent odor that occurs naturally in the stratosphere. |
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Term
| Why does ozone harm living organisms? |
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Definition
| It is a very reactive oxidising agent |
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Term
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Definition
| It forms the ozone layer which absorbs 99% of the sun's harmful light and keeps the temperature on Earth stable. |
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Term
| Where is the ozone layer? |
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Definition
| Between 15 and 45 km above the Earth's surface |
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Term
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Definition
| UV light from the sun splits O2 molecules into highly reactive oxygen free radicals, which then react with unbroken O2 molecules to form O3; can be reversed |
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Term
| Why can ozone be split more easily than O2? |
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Definition
| It forms three bonds which share electrons over the entire molecule and which are weaker than O2's double bond; the can be broken by long wavelength light. |
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Term
| Which two pollutants cause ozone depletion? |
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Definition
| CFCs (chlorofluorocarbons; freons) and nitric oxide (NO). |
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Term
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Definition
| In spray cans, old refrigerators and air conditioners, fire extinguishers. |
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Term
| What happens to CFCs when released? |
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Definition
| They don't decompose and are turned into very reactive chlorine free radicals by UV light. |
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Term
| How do CFCs lead to ozone depletion? |
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Definition
| Chlorine free radicals react with O3 and break it down to O2 (and ClO) |
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Term
| How does nitric oxide lead to ozone depletion? |
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Definition
| Nitric oxide from aircraft engines reacts with O3 and breaks it down to O2 (and NO2) |
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Term
| What does ozone depletion lead to? |
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Definition
| More harmful UV light reaches Earth; increased risk of melanomas, eye cataracts, sunburn, genetic mutations, climate changes and plant growth suppression. |
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Term
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Definition
| Because of their lack of reactivity, low toxicity and low flammability. |
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Term
| What are alternatives to CFCs? |
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Definition
| -> Must not contain C-Cl bonds: hydrocarbons, hydrochlorofluorocarbons, fluorocarbons and hydrofluorocarbons (HFCs) |
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