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46 Cards in this Set
- Front
- Back
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Why is greenhouse effect important |
Without it earth would be too cold to support life |
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What gases are greenhouse gases? |
Carbon dioxide, water and methane |
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What is the greenhouse effect |
Where gases in the earths atmosphere prevent some infrared radiation from escaping |
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What type of pollution is caused by hydrocarbons? |
React with NOx to form ground level ozone which leads to respiratory problems |
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What type of pollution is caused by NOx? |
Acid rain and photochemical smog |
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What type of pollution is caused by SO2 |
Acid rain |
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What type of pollution is caused by C? |
Particles worsen asthma |
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What type of pollution is caused by CO? |
Toxic gas |
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What type of pollution is caused by CO2? |
Global warming |
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How is fuel ignited in an internal combustion engine? |
Extreme temperature spark |
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What are the 4 stages in an internal combustion engine? |
Intake, compression, combustion, exhaust |
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What is soot? |
Carbon particulates |
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When is soot formed? |
When there is a very limited supply of oxygen |
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Why is carbon monoxide toxic? |
Bind to haemoglobin in red blood cells preventing oxygen from being carried by them |
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3 properties of carbon monoxide |
Toxic, colourless, odourless |
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What is formed in incomplete combustion? |
Carbon monoxide and water |
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What is produced in catalytic cracking? |
Mainly aromatic hydrocarbons and motor fuels |
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What is produced in thermal cracking? |
High percentage of alkenes and some short chain alkanes |
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What is the purpose of the honeycomb structure |
To increase surface area and therefore rate of reaction |
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What are the conditions for catalttical cracking |
800 to 1000k, 1 to 2 atm, zeolite catalyst |
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What is a zeolite |
A acidic mineral with a honeycomb structure made from aluminium oxide and silicon dioxide |
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Why is thermal cracking so short? |
For prevent complete decomposition of the hydrocarbon |
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What is the time frame for thermal cracking? |
1s |
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Give the conditions for thermal cracking |
1000 to 1200k, up to 70 atm |
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Why do small chains have lower boiling points |
Less atoms in chain so less VDW forces between them |
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What is a fraction |
A group of compounds with similar boiling points that are removed at the same level of the frzctionating column |
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Why do branches chains have lower melting points |
Smaller surface area so fewer VDW attaractions |
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What IMF exists between hydrocarbon chains |
Van der waals |
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What are hydrocarbons non polar |
The electronegativity difference between carbon and hydrogen is very small |
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how is the co2 in the atmosphere produced |
Respiration and combustion |
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How is the methane in the atmosphere produced?. |
Byproduct of sheep and cattle farming |
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What is the ph of normal rain water |
5.5 |
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Why is rain water a weak acid |
Co2 present in atmosphere |
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What ph is acid rain? |
Lower than 5.5 |
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What are the problems associated with acid rain? |
Destroys trees and vegetation, corroded buildings and kills fish in lakes |
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What causes photochemical smog? |
Pungent, toxic gases and minute solid particles suspended in air |
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When is smog formed? |
When NOx, SO2 or unburnt hydrocarbons react with sunlight |
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What health problems are associated with smog? |
Irritated eyes, nasal congestion, emphysema |
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What is the purpose of a catalytic converter? |
Converts toxic compounds from the internal combustion engine into less harmful products |
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What is a catalytic converter made of? |
A ceramic honeycomb covered in thin layer or platinum or rhodium |
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Which elements are acting as catalysts? |
Platinum or rhodium |
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2NO (g) + 2CO (g) = |
2CO2 (g) + N2 (g) |
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C8H18 (g) + 25NO(g) = |
8CO2 (g) + 12.5N2 (g) + 9H2O(g) |
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What is the process used to remove sulfur compunds from combustion emissions called? |
Flue gas desulfurisation |
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What happens in flue gas desulfurisation |
Gases are passed through a wet slurry of CaO or CaCo3 |
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What do the CaO or CaCO3 do in flue gas desulfurisation |
Neutralise the acidic SO2 |
