Hydrocarbon - compound containing only hydrogen and carbon atoms.
Crude Oil
Formed OVER millions of years from remains of plankton that were BURIED IN MUD
Crude oil is a finite resource
Alkenes general formula
CnH2n
Alkanes general formula
CnH2n+2
Alkanes are SATURATED hydrocarbons - carbon atoms are fully bonded to the Hydrogen atoms
Hydrocarbons
Flammability - as the size of HC increases, flammability decreases
Boiling Point - as the size of HC increases, BP increases
Viscosity - as the size of HC increases, viscosity increases
Short-chain hydrocarbons: low boiling point, extremely flammable, less viscous/thick/runny
Complete combustion
produce water (vapour) and carbon dioxide
During combustion, carbon and hydrogen atoms in fuel react with oxygen - they are both then oxidised, become CO2 and H2O
Feedstock
chemical used to make other chemicals eg solvents, lubricants
How to separate crude oil using fractional distillation:
crude oil is heated, evaporated, vaporised, gases are condensed and then fractions have different boiling points and are collected at different levels depending upon boiling point
Large chain hydrocarbons are not very flammable - do not make good fuels - low demand for them
Due to Long-chain HC in low demand for fuels, they convert it to short-chain HC by cracking
Cracking breaks down long-chain HC's into short-chain, useful HC's
Two ways of cracking
Catalytic cracking: use high temperature and catalyst
Steam Cracking: use high temperature and steam
Alkenes are more reactive and useful than alkanes
Alkenes test
Bromine water, shake the alkene with bromine water, turns water from orange to colourless
