3.2.1 Alkanes and Petroleum Flashcards
Alkanes general formula
CnH2n+2
Alkanes are made up of which element(s)
hydrocarbons
Alkanes
saturated or unsaturated?
saturated, contain only single bonds
Cycloalkanes
Ring of carbon atoms with 2 hydrogen atoms attached to each carbon
Cycloalkanes
general formula
CnH2n
Crude oil made up of
mainly alkanes
Petroleum
(fancy) word for crude oil
Petroleum made up of
mixture of hydrocarbons
mainly alkanes
Separation of crude oil technique
fractional distillation
Fractional distillation
brief method
crude oil vaporised at 350 degrees C
into fractionating column and rises
crude oil cools as it moves up
different fractions condense at different levels
Hydrocarbons with highest boiling points in crude oil …
don’t vaporise,
run to the bottom
form a residue (bitumen)
Hydrocarbons with lowest boiling points in crude oil…
don’t condense
drawn off as gases at top of column
Shorter chain hydrocarbons in crude oil have …
lower boiling points
Heavier fractions are
cracked
Cracking
breaking long-chain alkanes into smaller hydrocarbons by breaking c-c bonds
Two types of cracking
thermal and catalytic
Thermal cracking
conditions
high temp and high pressures
up to 1000 degrees C and 70 atm
Thermal cracking
products
produces lots of alkenes
used to make valuable products eg: polymers for plastics
Catalytic cracking
conditions
zeolite catalyst
slight pressure and high temp (about 450 degrees C)
Catalytic cracking
products
produces mainly aromatic hydrocarbons and motor fuels
Catalytic cracking
advantages
cuts costs
reaction done at lower temp and pressure
catalyst also speeds up reaction
