Fichas
Chlorofluorocarbons
Fichas del conjunto (16)
- 1What are the properties of chlorofluorocarbons (CFCs)?Very stable
Volatile
Non-flammable
Non-toxic - 2What were CFCs used in?Fridges
Aerosol cans
Dry cleaning
Air-conditioning - 3What was the problem with using CFCs?CFCs were destroying the ozone layer
- 4Complete 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.
- 5Ozone is formed naturally in what type of reaction?Free radical substation
- 6Describe the formation of ozone from oxygen, giving the symbol equationsAn 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 - 7Describe the process by which CFCs destroy the ozone layer, including the chemical equationsCFCs 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 - 8Give the overall symbol equation for the destruction of ozoneO₃ + O• --> 2O₂
- 9Name another type of compound that destroys ozone, other than CFCsNitrogen oxides (NO• free radicals)
- 10Nitrogen oxides are produced by...Car and aircraft engines
Thunderstorms - 11TRUE OR FALSE: NO• free radicals affect ozone in the same way as chlorine radicalsTRUE
- 12CFCs were banned because of the environmental causes. There were, however, a few permitted uses. What were they?Medical inhalers
Fire extinguishers used in submarines - 13Name three alternatives to CFCsHCFCs (hydrochlorofluorocarbons)
HFCs (hydrofluorocarbons)
Hydrocarbons - 14On average, how many years does it take for CFCs to leave the atmosphere?90 years
- 15Why 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) - 16TRUE OR FALSE: HFCs don't affect the ozone layerTRUE
They don't contain chlorine (no Cl•)
Información
- Descripción
- El usuario ha eliminado su información de asignaturas Fichas sobre Chlorofluorocarbons, creado por Usuario eliminado el 12/03/2018.
- Creado por
- Usuario eliminado · mar 2018
- Actualizado
- 12 mar 2018
- Visitas
- 7
- Historial
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- Creado por Yinka F · 8 mar 2018
- Copiado por Yinka F · 12 mar 2018
- Valoración