4.1-4.4 Fuels From Crude Oil/Fractional Distillation/Burning Fuels/Cleaner Fuels Flashcards
What is different about different length hydrocarbons?
They have different boiling points
Why does crude oil need to be separated to make useful fuels?
Because the compounds in the crude oil burn at different temperatures
What are fractions?
Liquids with different boiling points that have been separated from a mixture of liquids
How can we separate a mixture of liquids with different boiling points?
Distillation
What is the name given to separating crude oil by distillation?
Fractional distillation
Define fuel
A substance that releases energy when it’s burned
What is crude oil?
A mixture of hydrocarbons that comes directly from the earths crust
Describe the: Boiling point Volatility Viscosity Flammability For a short chain hydrocarbon
Boiling point: low
Volatility: high
Viscosity: low
Flammability: high (clean)
Describe the: Boiling point Volatility Viscosity Flammability For a long chain hydrocarbon
Boiling point: high
Volatility: low
Viscosity: high
Flammability: low (smokey)
What is volatility?
How easy it is to turn into a gas
What is viscosity?
How thick/runny it is
What are alkanes?
Chains of hydrocarbons without a double bond
Give the general formula for alkanes
CnH2n+2
Why do we call alkanes saturated hydrocarbons?
They contain as many hydrogen atoms as possible in each molecule
Write the molecular formula for ethane
C2H6
Write the displayed formula for ethane
H H
| |
H- C - C- H
| |
H HName the numerical order of the hydrocarbons
Meth- Eth- Prop- But- Pent-
Where does fractional distillation take place?
Refineries
What does the boiling point of a hydrocarbon depend on?
It’s size
How does fractional distillation work?
The crude oil is vaporised and enters a tall fractionating column. The column gets colder the higher up you go. The different length hydrocarbons condense at different points so are then collected at the area where they condensed, as a liquid
Where do the longest hydrocarbons end up in the fractionating column?
At the bottom due to their high boiling points
Where are the shortest hydrocarbons collected in the fractionating column?
At the top
Name the order of the products from fractional distillation in their order from highest to lowest
- bottled gas
- petroleum gas
- naphtha (chemicals)
- kerosene (aircrafts)
- diesel oil (cars, buses)
- fuel oil (ship fuel)
- bitumen (roads)
- residue (roads)
What properties would you expect for fractions higher up the fractionating column?
- lower viscosity
- lower boiling points
- higher volatility
- higher flammability
What is the complete combustion of hydrocarbons?
When the hydrocarbons react fully with oxygen. They are oxidised to carbon dioxide and water
Write a word equation for the complete combustion of ethane
Ethane + oxygen –> carbon dioxide + water
What colour does a flame burn if there is complete combustion?
Blue
What is the incomplete combustion of hydrocarbons?
When there is not enough oxygen to oxidise the hydrocarbons so some carbon is left over as particulates or carbon monoxide
What colour does a flame burn if there is incomplete combustion?
Orange/yellow
Name four possible products of the incomplete combustion of a hydrocarbon
- carbon monoxide
- carbon particulates
- unburnt hydrocarbon
- soot
- water
Other than hydrocarbons, what type of compounds do most fossil fuels contain?
Sulphur compounds
What happens when the sulphur dioxide, from burning fuels, is released into the air?
It causes acid rain
Why could nitrogen and oxygen combine to form nitrogen oxides when fuels burn?
There are high temperatures that give them energy to bond together
What does nitrogen oxide cause?
Acid does
What gas causes particulates?
Carbon monoxide
Why might incomplete combustion happen?
Because there is a limited supply of air
What do scientists believe causes global dimming?
Particulates
Why do particulates cause global dimming?
The particulates, as solid tiny particles, reflect sunlight away from the earth so causes global dimming
How is acid rain formed?
Sulphur dioxide and nitrogen oxides react with oxygen in the air and dissolves in water to produce acid rain
How can we reduce the amount of sulphur dioxide being produced? Name 2 ways
- remove the sulphur from the fuel before you burn it
* remove sulphur dioxide from the waste gases produced from power stations
Name a way we can remove carbon monoxide and nitrogen oxides
Exhaust systems of cars are fitted with catalytic converters
How can we prevent particulates from being released?
Filter them so they aren’t released
Name 5 products we can obtain from crude oils
- medicine
- fabric
- dye
- plastics
- fuels
What does crude oil contain?
Hydrocarbons (and few other compounds)
