4.7 organic chemistry Flashcards
what is crude oil and what is it made from
finite resource found in rocks. Crude oil is the remains of an ancient biomass consisting of plankton that was buried in mud
what is crude oil a mixture of
a number of compounds. Most compounds are hydrocarbons, which are molecules made up from only hydrogen and carbon atoms.
what are most hydrocarbons in crude oil called
alkanes, which only contain single covalent bonds making them saturated hydrocarbons
general formular for the homologous series of alkanes
Cn H2n+2
formula of methane
CH4
formula of ethane
C2H6
formula of propane
C3H8
formula of butane
C4H10
products of hydrocarbon through combustion
complete combustion: Carbon dioxide and Water.
A larger hydrocarbon molecule/chain means what?
lower flammability and volatility (how easily a liquid vaporises), higher viscosity and higher boiling points
why do larger hydrocarbon molecules / chains have higher boiling points
because the molecules are larger, the intermolecular forces are stronger/large, so more energy is required to break them
products of incomplete combustion
carbon monixide, carbon particles known as soot
describe the processes in fractional distillation
crude oil is heated outside of column where most of it vapourises, mixture of vapour and liquids are passed into the bottom of the fractionating tower. Inside the tower is a concentration gradient, meaning that the top of the tower is cooler and the bottom is hotter. vapour rises up the column and cools and then condenses. each fraction has a different boiling point and condenses at different levels Larger/longer hydrocarbons condense towards the bottom as there are more intermolecular forces which require more energy to break. smaller hydrocarbons condense towards the top.
uses of LPG
cooking equipment, heating appliances
uses of petrol
fuel for cars, heating appliances, produces electricity
uses of kerosene
fuel for jet
uses of diesel oil
fuel for cars, trains, large vehicles
uses of heavy fuel oil
fuel for large ship engines / marine boats, power stations
uses of bitumen
used to make tarmac in road making
what is the cracking of hydrocarbons
when larger hydrocarbons are broken down to produce smaller and more useful molecules
describe the cracking process
heating the hydrocarbons to vapourise them, the vapours are either passed over a hot catalyst or mixed with steam and heated to a very high temperature
uses of cracking products
high demand for fuels with small molecules, like petrol and diesel
alkanes are used to produce polymers and as starting materials for the production of many other chemicals
what type of reaction is cracking
thermal decomposition reactions
products of cracking
alkanes and unsaturated hydrocarbons called alkenes