Fuels
Fossil fuels and hydrocarbons
- The three fossil fuels: coal, natural gas (mostly methane), petroleum (crude oil).
- A hydrocarbon is a compound of hydrogen and carbon only.
- Petroleum is a mixture of many hydrocarbons.
Practice
A hydrocarbon is a compound made of:
Hydrocarbons contain only hydrogen and carbon; petroleum is a mixture of them.
Practice
The main hydrocarbon in natural gas is:
Natural gas is mostly methane (CH4).
Fractional distillation
- Petroleum is separated into fractions by fractional distillation: heated, the hydrocarbons rise up a fractionating column that is hot at the bottom, cool at the top.
- Going up the column, fractions have shorter chains, higher volatility, lower boiling points, lower viscosity.
- Fractions: refinery gas, petrol, naphtha, kerosene (jet fuel), diesel, fuel oil, lubricating oil, bitumen (roads).
Practice
Going UP the fractionating column, the fractions have:
The top is cooler, collecting small, volatile, low-boiling, low-viscosity molecules.
You've got it
Key idea
- fossil fuels: coal, natural gas (methane), petroleum; a hydrocarbon is H + C only
- fractional distillation splits crude oil by boiling point (hot bottom, cool top)
- up the column: shorter chains, lower boiling point, more volatile, less viscous