sc20, fuels (paper 2) Flashcards
what is a crude oil
a fossil fuel formed over millions of years from ancient remains of marine organisms
define hydrocarbon
compounds of carbon and hydrogen atoms ONLY
what are the different possible bonds in a hydrocarbon molecule
- carbon __ carbon bonds
- carbon __ hydrogen bonds
what are the two things hydrocarbon molecules can consist of
- chains (with or without branches)
- rings of carbon atoms
what is a finite resource
- no longer being made or
- being made extremely slowly
why are sources from crude oil useful
- hydrocarbons are useful as fuels
- and as feedstock for the petrochemical industry
define feedstock
starting material for an industrial chemical process
define petrochemical industry
involves the use and manufacture of substances from crude oil
why can you use fractional distillation to seperate crude oil into simpler, more useful mixtures
the different hydrocarbons have different boiling points
what is a fraction in terms of crude oil
a mixture of hydrocarbons with similar boiling points and number of carbon atoms
what happens to the gas fraction in fractional distilaltion for crude oil
doesn’t condense and leaves at the top
what happens to the bitumen fraction in fractional distilaltion for crude oil
doesn’t evaporate and leaves at the bottom
what happens to the ‘other’ fraction in fractional distilaltion for crude oil
they are liquid at room temp and are useful as fuels
true or false: most hydrocarbons are alkanes
true
true or false: most hydrocarbons are alkenes
false
what happens as the number of carbon and hydrogen atoms in a hydrocarbon molecule increase
- the strength of the intermolecular forces increases
- more energy must be transfered to overcome these forces
- the boiling point increases
what is an alkane
form a homologous series of hydrocarbons
what is a homologous series
a series of compounds:
- in which molecular formulae of neighbouring members differ by CH2
- that show a gradual variation in physical properties
- that have similar chemical properties
what happens when alkanes undergo complete combustion
they form carbon dioxide and water vapour
what do alkanes end in
ane
why does incomplete combustion happen
when the supply of oxygen to a burning fuel is limited
what happens in complete combustion
- hydrogen is oxidised to water vapout
- carbon is oxidised to carbon dioxide
- energy is transferred to surroundings by radiation as heat and light