Chemistry of the Air
- Created by: Molly Pursell
- Created on: 28-12-12 15:34
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- Chemistry of the Air
- Global Warming
- Greenhouse Gases include; CO2, CH4 and H2O
- Greenhouse effect depends on 1) Atmospheric Concentration 2) Ability to absorb Infrared Radiation
- Covalent bonds have various strengths due to different masses of the atoms and either end of the bond. Therefore, they vibrate at different frequencies
- Frequency of Vibration can be found by detecting when the molecules absorb electro-magneitc radiation
- Various types of vibrations are possible; Symmetric Stretching, Bending and Asymmetric Stretching
- The frequencies and found in the infrared part of electro-magnetic spectrum and can be found using infrared spectroscopy
- The Greenhouse Effect
- Process; Radiation (Ultra Violet, Visible and Infra red) comes from the sun, 47% reaches the Earth's surface, Earth re-emits energy, 70% of re-emitted energy escapes
- Increase conc. in greenhouse gases leads to GLOBAL WARMING
- CCS (Carbon Capture and Storage) is when waste CO2 is...
- 1) Injected as a liquid deep into oceans
- 2) Stored in deep geographical formations
- 3) Reacted with metal oxides to form carbonate minerals - e.g. MgO + CO2 --> MgCO3
- Depletion of the Ozone Layer
- Ozone
- Ozone is a reactive and poisonous gas but it protects us from harmful UV radiation which would affect life o Earth (e.g. Cancer)
- Ozone in the stratosphere breaks down naturally - 2O3 --> 3O2
- Ozone (trioxyen) can break up to give an ordinary oxygen and a radical - O3 --> O + O2
- UV light supplies the energy for this process which is why the ozone layer is important
- CFC's
- CFC's break down in presense of UV light to form chlorine radicals - CCl2F2 --> Cl + CClF2
- Chlorine radicals react with ozone - O3 + Cl --> ClO + O2
- Chlroine radicals are regenerated - ClO + O --> O2 + Cl
- NOx
- Oxides of nitrogen (NOx) are formed during thunderstorms or by aircraft breakdown to give NO (nitrogen monoxide) which catalysis the break down of ozone
- 1) O3 + NO --> NO2 + O2
- 2) NO2 + O --> O2 + NO
- Oxides of nitrogen (NOx) are formed during thunderstorms or by aircraft breakdown to give NO (nitrogen monoxide) which catalysis the break down of ozone
- Ozone
- Pollutant Gases from Internal Combustion Engines
- CO, is formed by incomplete combustion of hydrocarbon. It is poisonous, combines with haemoglobin and prevents O2 being carried
- NOx, formed by a combination of atmos nitrogen and oxygen under high temps. It aids photochemical smog (irritates eyes, nose and throat), aids formation of low level ozone which affects plant growth
- CxHy, hydrocarbonsthat have not been combusted. They are toxic
- Catalytic Converters
- Operation
- 2NO(g) + 2CO(g) --> N2(g) + 2CO2(g)
- Unburnt hydrocarbons are converted into CO2 and H2O
- Catalysts are rare metals -RHODIUM, PALLADIUM - which are finallly divided for greater surface area (more active sites)
- Stages
- 1) Adsorption; NO and CO seet out active sites on catalyst surface, they're bonds with surface weakens bonds in molecule, this makes reactions easier
- 2) Reaction; Being held on surface increases chance of favourable collisions, bonds break and re-arrange
- 3) Desorption; Products of N2 and CO2 are then released from the active sites
- Operation
- Global Warming
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