Alkanes Flashcards
What is the general formula for an alkane?
CnH2n+2 e.g. C2H6, C3H8
Are they saturated or unsaturated?
Saturated as they contain no C=C bond.
Polar or non-polar?
Non polar
What are the only forces of attraction between neighbouring molecules?
Van der Waals
What happens as chain length increases?
Boiling point increases as the Van der Waals forces of attraction between the molecules increases. The viscosity increases.
What happens when they become branched?
The more branching there is the lower the boiling point, because there are less Van der Waals forces between the molecules as they cannot pack as tightly together.
What is combustion? Complete and incomplete?
Combustion if the chemical reaction of a fuel with oxygen releasing heat and forming oxides.
Complete - Plentiful supply of O2
Incomplete - Limited supply of O2
What does the complete combustion form
Carbon Dioxide and Water
What does the incomplete combustion form
Carbon monoxide and water and soot
What colour do compounds with a high % carbon burn
Smoky orange flame
What colour do compounds with a low % carbon burn
Clean blue
How is the temperature of the earth raised?
Greenhouse gases absorb infrared radiation emitted from the earths surface and reflect it back to earth.
What are the effects of this raised temperature?
Climate change, increased sea levels, melting of polar ice caps and flooding of low-level regions.
What method are used limit the production of greenhouses gases?
1) Removing Sulfur from fuels before combustion
2) Using catalytic converters
3) Scrubbing emissions
4) Using renewable energy resources
What do catalytic converters do?
1) Convert CO to CO2
2) Oxides of nitrogen are converted to N2 and O2
3) Unburnt hydrocarbons are oxidised to CO2 AND H2O
