Crude Oil Flashcards
What is crude oil?
mixture of hydrocarbons
Hydrocarbons are a form of organic molecule. What does this mean?
a carbon compound (except carbon dioxide and carbonates)
Is crude oil renewable or non-renewable?
non-renewable
How was crude oil formed?
- dead plants/animals fall to bottom of sea
- layers of sediment on top of them
- shells/ skeletons form limestone
- soft tissue gradually changed by high temperatures and pressure into crude oil
How does fractional distillation work?
- crude oil is separated by heating and vaporising
- passed into fractionating column which has a temperature gradient (cooler at top/ hotter at bottom)
- different fractions have different boiling points
- longer hydrocarbons have high B.P so condense and drain at bottom
- smaller hydrocarbons have low B.P so rise up and condense near top
What are the purpose of bubble caps?
prevent separated liquids running back into column and remixing
What is a fraction?
a mixture of hydrocarbons with similar boiling points
Order of fractions
- refinery gases
- gasoline
- kerosene
- diesel
- fuel oil
- bitumen
What happens to the boiling point as you go down the fractions?
- increases
- requires more heat energy to break strong bonds
What happens to the viscosity as you go down the fractions?
- increases
- greater attraction between molecules
What happens to the volatility as you go down the fractions?
- decreases
- stronger attractions so evaporate less slowly
What happens to the ability to burn as you go down the fractions?
- burn less easily
What type of reaction is cracking?
thermal decomposition
In industry, how is cracking carried out? what conditions needed?
- vaporised hydrocarbons
- passed over a powdered catalyst (alumina/ silica/ porous pot)
- temp of 600-700c
In lab, how is cracking carried out?
- heat mineral wool soaked in paraffin at end of boiling tube
- heat catalyst in middle of boiling tube and then alternate heat until paraffin vaporises and catalyst glows red
- paraffin vapour cracks when passes over catalyst
- alkanes collect at end of boiling tube
- alkenes collect in delivery tube through water
