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Fichas del conjunto (21)
- 1Briefly describe the greenhouse effect:Radiation from the sun reaches planet
Radiation absorbed and re-emmitted as IR radiation
Absorbed by gases
Gases reemit IR radiation as energy - 2Name the three greenhouse gasesWater vapour - H2O
Methane - CH4
Carbon dioxide - CO2 - 3How do gases absorb radiation?BONDS VIBRATE
Different gases absorb different amounts of IR radiation. - 4What three factors determine the impact of a greenhouse gas?1. Its CONCENTRATION in the atmosphere (relative abundance)
2. It's ABILITY to ABSORB IR radiation
3. It's LIFETIME in the atmosphere - 5What does GWP stand for?Global Warming Potential.
Consists of three factors - 6Renewable resourcesAlternative energy sources like wind, solar, tidal and nuclear reduce CO2 pollution.
Fossil fuels necessary to meet energy demands - 7Carbon Capture Storage (CCS) STORAGE OPTIONCO2 can be captured and stored to reduce pollution:
- In disused oil refineries
-Deep in oceans
- In underground deposits - 8Carbon Capture Storage (CCS) REACTION OPTIONMineral storage reduces CO2 by converting it to minerals such as carbonates:
CaO + CO2 ==>> CaCO3 - 9Ozone layer benefits:Acts like "sunglasses" filtering out harmful radiation (UV-c)
- 10Ozone formation:uv
O2 ==> 2O*
The radical reacts with an O2 molecule forming O3
O* + O2 ==> O3 (+heat) - 11How does the ozone layer work?Ozone absorbs UV radiation breaking it into O2 and O. O and O2 then react reforming O3 and producing heat.
Overall UV is converted to heat energy and this process continues creating an equilibrium:
O + O2 <==> O3 - 12Ozone depletion INITIATIONUV radiation breaks C--Cl bonds releasing chlorine radicals into the atmosphere.
CFCl3 ==> CFCl2* + Cl* - 13Ozone depletion PROPOGATIONCl* + O3 ==> ClO* + O2
ClO* + O ==> Cl* + O2
overall: O + O3 ==> 2O
The chlorine radicals catalyse the decomposition of ozone with the chlorine radical coming out unchanged. - 14Ozone Depletion: *NONitrogen oxide is formed from lightening strikes and aircraft engines.
Reaction mechanism similar to chlorine radicals but with nitrogen oxide radicals. - 15Air pollution: COCarbon monoxide:
- poisonous, reduces oxygen levels in blood
- reduces ability to perform complex tasks - 16Air pollution: NOxNitrogen oxides:
- Formed at high temperatures in a car engine/exhaust.
- produces low level ozone (respiratory problems)
- Acid rain - 17Air pollution: VOCsVolatile organic compounds:
- unburnt fuels released in exhaust fumes
- can be carcinogenic
- react with NO2 forming low-level ozone - 18Catalytic converters 2 typesHoneycomb structure increases surface area
(1) Oxidation catalytic converters
(convert CO to CO2 and oxidise VOCs)
(2) 3-way catalysts
(convert CO to CO2 removes NO and oxidises VOCs) - 19How does a catalyst work?HETEROGENOUS:
ADSORPTION: Molecules held to surface
REACTION: Temporary bonds form. Molecule's bonds weaken. Reaction occurs.
DESORPTION: Products desorbed from catalyst. Diffuse away. - 20What are the 12 principles of sustainability?1. PREVENTION
2. ATOM ECONOMY
3. Less HAZARDOUS chemical synthesis
4. Design SAFER chemicals
5. Safer solvents and auxiliaries
6. Design for energy EFFICIENCY
7. Use of RENEWABLE FEEDSTOCKS
8. Reduce derivatives
9. CATALYSTS
10. Design for DEGRADATION
11. Real time analysis for POLLUTION prevention
12. Inherently saver chemistry for ACCIDENT PREVENTION - 21CO2 villain to saviour: Outline uses for CO21. In foam. Used as a replacement to CFCs to expand polystyrene
2. Solvent. Can be turned to scCO2 and then used to dissolve other chemicals.
3. Decaffeinating coffee
4. Producing fizz in beer
5. Dry cleaning
6. Chemical synthesis
7. Toxic waste treatment
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- (AS Chemistry) Chemistry Fichas sobre Resources, creado por nicole_j_baldwin el 22/03/2015.
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