Term
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Definition
| A naturally occurring component of the stratosphere. Pale blue gas with a strong odour, and very reactive. |
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Term
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Definition
| High energy (UV/Sunlight) splits the double bond in O2, creating oxygen atoms, which are extremely reactive and known as free radicals. These oxygen atoms then react with O2 to form O3. |
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Term
| What pollutants are depleting ozone? |
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Definition
| CFCs and Nitric oxide. CFCs are found in spray cans and old refrigerators and nitric oxide is formed in aircraft engines, where the high temperatures where N2 and O2 react with the ozone. |
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Term
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Definition
| Hydrocarbons, hydrochlorofluorocarbons, fluorocarbons and HFCs. |
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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
| Diatomic oxygen and ozone (triatomic oxygen) are... |
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Definition
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Term
| Compared to ozone, O2 has a... |
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Definition
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Term
| To break O=O bonds, radiation of ... is needed. |
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Definition
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Term
| To break O=O-O bonds, radiation of ... is needed. |
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Definition
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Term
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Definition
| harmful UV rays that oxygen does not absorb. |
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Term
| What happens to chloroflourocarbons in the upper atmosphere? |
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Definition
| UV light breaks the C-Cl bonds to form chlorine free radicals (initiation). |
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Term
| What happens to the chlorine free radicals form the CFCs? |
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Definition
| They bond with ozone to form chlorine monoxide free radicals and O2 (propagation) |
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Term
| What happens during the termination step of free radical reactions? |
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Definition
| Two free radicals can react to form O2 and another free radical |
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Term
| What do chlorine free radicals and nitrogen monoxide do to ozone? |
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Definition
| They catalyse the reaction with O to form O2 |
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Term
| What does NO do to ozone? |
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Definition
| It reacts to form NO2 and O2. The NO2 can react with O free radicals to form NO and O2 |
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Term
| Where on the planet is the most ozone depletion? |
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Definition
| In polar regions. Pollutants are trapped in winter and massively released in summer (chlorine free radicals catalyse the destruction of the ozone layer) |
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Term
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Definition
| It is naturally occuring component of the stratospere.It is very pale bluish gas with an accrid odour. |
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Term
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Definition
| It is about 15 to 45 km above the Earth's surface and holds much of the air's ozone. |
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Term
| How is Ozone formed in the upper atmoshpere? |
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Definition
| The photo-dissociation of oxygen molecule by uv light represents the principle mechanism of ozone's formation in the upper atmosphere. |
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Term
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Definition
| uv light from the sum splits the strong double bond in 02 molecules into oxygen atoms which are extremely free radicals containing unpaired electrons. |
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Term
| How can ozone molecule be broken? |
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Definition
| Ozone molecule can be broken down by lights of uv which have longer wavelength and with less energy. |
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Term
| Why does the oxygen molecule require more energy than ozone gas for the process of dissociation? |
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Definition
| Since,the wavelength of light is inversely proportional to energy,the stronger double bond in oxygen molecule requires radiation of lower wavelength compared with the disassociation of ozone which requires higher wavelength. |
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Term
| What is the range of harmful uv rays absorbed by ozone? |
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Definition
| 240-330 nm that oxygen cannot absorb. |
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Term
| What is the initiation step in the depletion of ozone? |
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Definition
| In the upper atmosphere, uv light is able to break the weaker C-Cl bonds by homolysis to produce chlorine free radicals . |
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Term
| What is propagation step in this process? |
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Definition
| The chlorine free radical can react with ozone to produce oxygen molecule and one free radical. |
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Term
| What is termination step? |
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Definition
| The newly formed chlorine freee radical can also react with an oxygen free radical to form diatomic oxygen molecule and regenerate the chlorine free radical. |
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Term
| Name two gases responsible for depletion of ozone molecule? |
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Definition
| Methane and Carbon-di-oxide |
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Term
| How do CFC's deplete ozone layer? |
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Definition
| CFC's are chemically inert, they do not decompose but float slowly through the atmosphere into the startosphere. When they reach the unfiltered uv rays of the sun,they are turned into extremely reactive chlorine atoms with an unpaired electron ,called free radical and thus result in the depletionof ozone molecule. |
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Term
| What are examples of allotropes? |
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Definition
| O2 -> Oxygen, and 03 -> Ozone |
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Term
| Which bond amongst the mentioned allotropes is the strongest? |
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Definition
| The double bond in oxygen is relatively stronger compared to that of Ozone. |
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Term
| What can you conclude about the energies of the allotropes after finding out which one is stronger? |
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Definition
| The fact that the double bond in oxygen is stronger tells us the fact that more energy is going to be required to break the oxygen bond whereas, in ozone, relatively less energy is required as the bond isn't as strong to that of Oxygen |
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Term
| What is the relationship of wavelength of light and it's energy? |
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Definition
| The relationship of wavelength of light and it's energy is inversely proportional |
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Term
| After finding out the relationship between wavelength of light and it's energy, what can you conclude about the allotropes? |
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Definition
| The stronger the bonds are, the lower the radiation of wavelength. Therefore the ozone bonds that are weak relative to the oxygen bonds, require higher wavelength whereas the oxygen bonds require relatively less. |
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Term
| What are CFCs and their uses? |
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Definition
| CFCs are chluorofluorocarbons that are stable compounds and have variety of uses. For exampe refrigeration, propellants in aerosol sprays etc. |
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Term
| How are cholrine free radicals produced in the initiation step? |
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Definition
| The chlorine free radicals are produced in the initiation step when the strong uv light easily penetrates the through the weak C-Cl bonds by homolysis . CCl2F2 + uv -> .CClF2 + .Cl |
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Term
| When does the propagation method come into play? |
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Definition
| When the chlorine free radicals react with ozone to produce an oxygen molecule and .ClO This is a propagation method where one free radical is used up and another is formed replacing it. |
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Term
| How is the chlorine free radical regenerated? |
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Definition
| When .ClO radical is formed; it can also possibly react with an oxygen free radical to form a diatomic oxygen molecule regenerating the chlorine free radical |
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Term
| Why was there a decrease in ozone concentrations in Antartica in the 1980s and 1990s? |
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Definition
| It was caused by the increase in ozone depleting pollutants |
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Term
| Why are some uv waves harmful? |
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Definition
| High energy uv excites electrons and breaks bonds in biologically important molecules such as DNA and can alter their properties |
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Term
| What are some alternatives to CFCs, and which is said to be the best option? |
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Definition
| Hydrocarbons, hydrochlorofluorocarbons, fluorocarbons and hydroflurocarbons. HFCs are best alternative. |
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Term
| Give the formula for insoluble carbonates to be converted to more soluble sulfates. |
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Definition
| CaCO3+H2SO4->CaSO4+H2O+CO2__and__MGCO3+H2SO4->MGSO4+H2O+CO2 |
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Term
| What are the 5 major primary pollutants in the atmosphere? |
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Definition
| CO, NOx, SOx, Particulates and VOCs |
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Term
| What are the anthropogenic sources of the 5 primary pollutants? |
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Definition
| CO (incomplete combustion of fossil fuels used fro transportation adn industry; forest fires), NOx (high temperature combustion in car engines, producing NO) , SOx (combustion of sulfur containing coal, smelting plants and sulfuric acid plants), Particulates (combustion of fossil fuels by industry, transportation, the break up of solid matter, industrial plants which produce smoke, soot, ash, and dust) and VOCs (petroleum extraction, refining, transporting and use; solvents, incomplete combustion of gasoline, coal and wood) |
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Term
| What is the pH of pure rain water? |
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Definition
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Term
| What is an equation for acid rain containing sulfur? |
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Definition
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Term
| What is an equation for acid rain containing sulfur? |
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Definition
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Term
Which of these is not released from burning fossil fuels? A.Carbon dioxide_x000D_
B. Sulphur dioxide_x000D_
C. Zinc oxide_x000D_
D. Nitrogen oxides |
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Definition
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Term
| How much more concentrated is a pH of 4 compared to a pH of 6.5? |
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Definition
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Term
| Name one natural source of methane? |
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Definition
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Term
| Name one man maid source of methane? |
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Definition
| Combustion of organic fuels |
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Term
| Give the formulae for incomplete combustion of gasoline? |
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Definition
| C8H18 + (17/2)O2 ---> 8CO + 9H2O |
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Term
| How is nitrogen dioxed produced in the atmosphere? |
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Definition
| 2 NO reacts with oxygen gas to oxidize and give NO2 |
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Term
| Name one green house gas. |
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Definition
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Term
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Definition
| Each of two or more different physical forms in which an element can exist. |
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Term
| Give an example of an allotrope. |
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Definition
| Graphite, charcoal, and diamond are all allotropes of carbon. |
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Term
| How many meters bove the ground is the ozone layer about found? |
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Definition
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Term
| What wavelength of light does oxygen gas absorb? |
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Definition
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Term
| What wavelength of light does ozone absorb? |
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Definition
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Term
| What are the steps of ozone depletion in chornological order? |
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Definition
| Intiation, Propgation and Termination |
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