C7 Hydrocarbons Flashcards
Crude oil
A fossil fuel
A finite resource
Hydrocarbons
Molecules made from carbon and hydrogen only
Smallest hydrocarbon is methane
Homologous series
All alkanes have the same general formula C2H2n+2
Fractional distillation
The mixture of oils in crude oil separated into fractions
Products from crude oil
Fuel- liquified petroleum gas(LPG), petrol,kerosene, diesel oil, heavy fuel oil
Petrochemicals- solvents, lubricants, polymers, detergents
Separating fractions
A fractional distillation column is used where the top is the coolest
Each oil is separated out at different points as the gases with low boiling points go to the top and heavier gas stay at the bottom
Why can be fractions be separated?
As molecules with larger chains have stronger bonds so have a higher boiling point than molecules in shorter weaker chains
Using fuels
Petrol and diesel in car engines
LPG in camping stoves
Kerosene in aircrafts
Heavy fuel oil in ships
What happens to the boiling point when molecules get larger
The boiling point increases
Larger molecules means
Boiling point and viscosity increases
Flammability decreases
What happens if you burn a hydrocarbon
Water and carbon dioxide are produced
Incomplete combustion
When a fuel burns in a shortage of oxygen
Products are water, carbon monoxide and carbon
Complete combustion
CH4 + 2O2 = CO2 + 2H2O
Carbon and hydrogen in fuels are oxidised
Supply and demand
The solution to the demand for petrol is cracking.
Cracking
Kerosene can be cracked into petrol
Essentially it is using a night temperature and a catalyst to break long molecules into smaller molecules that are in a greater demand. The alkenes produced can also help in the production of many other chemicals