carbon compounds as fuels and feedstock Flashcards
define “finite resource”
a resource that has an end
what is crude oil?
a complex mixture of hydrocarbons
describe how crude oil was made
crude oil is the remain of an ancient biomass consisting mainly of plankton that was buried in mud.
define the term hydrocarbon
molecules made up of hydrogen and carbon atoms only
when is the general formula of an alkane?
CnH2n+2
name the first 4 members of the alkanes
the first 4 members of the alkanes are methane, ethane, propane and butane.
write the molecular formula of butane
C4H10
write the molecular formula of propane
C3H6
Write the molecular formula of ethane
C2H6
write the molecular formula of methane
CH4
what is fractional distillation?
the hydrocarbon in crude oil are separated into fractions, each of which contains molecules with a similar number of carbon atoms
explain how fractional distillation works
crude oil is boiled enters the fractional column where it is hotter at bottom cooler at the top. The fractions have different boiling points and condense at different levels, with the heaviest fractions collected at bottom and lightest fractions collect at top.
how does alkane chain length affect:
- boiling point
- viscosity
- flammability
as the alkane chain length increases, the boiling point increases, the viscosity increases and the flammability decreases.
what is complete combustion?
the complete combustion of a hydrocarbon produces carbon dioxide and water
what is combustion?
the combustion of hydrocarbon fuels releases energy. during combustion, the carbon and hydrogen in the fuels are oxidised
what is “cracking”
the breaking of hydrocarbons into produce smaller, more useful alkane and alkene molecules
what are the 2 methods of cracking?
high temperature and catalyst or high temperature and steam.
describe the test for alkenes
decolourises bromine water ie. orange to colourless
what are alkenes used for?
alkenes are used to produce polymers and as starting materials for the production of many other chemicals
why is cracking necessary
to meet the high demand of more useful shorter alkenes that are in low supply
