Chlorofluorocarbons

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A level Chemistry (4.2 Alcohols, Haloalkanes and Analysis) Flashcards on Chlorofluorocarbons, created by Yinka F on 08/03/2018.
Yinka F
Flashcards by Yinka F, updated more than 1 year ago
Yinka F
Created by Yinka F over 6 years ago
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Question Answer
What are the properties of chlorofluorocarbons (CFCs)? Very stable Volatile Non-flammable Non-toxic
What were CFCs used in? Fridges Aerosol cans Dry cleaning Air-conditioning
What was the problem with using CFCs? CFCs were destroying the ozone layer
Complete the sentences: The ozone layer is in a layer of the atmosphere called the ______________. It contains most of the atmosphere's ________ molecules (O₃) and acts as a ___________ sunscreen. It absorbs a lot of the ____ radiation which can cause sunburn or even ________ ___________. The ozone layer is in a layer of the atmosphere called the STRATOSPHERE. It contains most of the atmosphere's OZONE molecules (O₃) and acts as a CHEMICAL sunscreen. It absorbs a lot of the UV radiation which can cause sunburn or even SKIN CANCER.
Ozone is formed naturally in what type of reaction? Free radical substation
Describe the formation of ozone from oxygen, giving the symbol equations An oxygen molecule is broken down into two free radicals by UV radiation: O₂ + hv --> 2O• The free radicals attack other oxygen molecules, forming ozone: O₂ + O• --> O₃
Describe the process by which CFCs destroy the ozone layer, including the chemical equations CFCs absorb high-energy UV radiation and split to form chlorine free radicals: CF₂Cl₂ + hv --> CF₂Cl• + Cl• These free radicals catalyse the destruction of ozone, setting up a chain reaction: Cl• + O₃ --> O₂ + ClO• ClO• + O• --> O₂ + Cl• The chlorine radical is regenerated and goes on to attack another ozone molecule
Give the overall symbol equation for the destruction of ozone O₃ + O• --> 2O₂
Name another type of compound that destroys ozone, other than CFCs Nitrogen oxides (NO• free radicals)
Nitrogen oxides are produced by... Car and aircraft engines Thunderstorms
TRUE OR FALSE: NO• free radicals affect ozone in the same way as chlorine radicals TRUE
CFCs were banned because of the environmental causes. There were, however, a few permitted uses. What were they? Medical inhalers Fire extinguishers used in submarines
Name three alternatives to CFCs HCFCs (hydrochlorofluorocarbons) HFCs (hydrofluorocarbons) Hydrocarbons
On average, how many years does it take for CFCs to leave the atmosphere? 90 years
Why are HCFCs, HFCs and hydrocarbons only temporary alternatives to CFCs? HCFCs still damage the ozone layer (though their effect is much smaller than that of CFCs) HCFCs, HFCs and hydrocarbons are greenhouse gases (they contribute to global warming)
TRUE OR FALSE: HFCs don't affect the ozone layer TRUE They don't contain chlorine (no Cl•)
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