C1.4 Flashcards
(24 cards)
What is crude oil a mixture of?
A mixture of a very large number of compounds, most of which are hydrocarbons.
What is a hydrocarbon?
A hydrocarbon is a compound made up of hydrogen atoms and carbon atoms ONLY.
What is a compound?
A compound consists of 3 or more elements chemically combined together.
What is the general formula for alkanes?
CnH2n+2
How many bonds can each carbon atom have?
4
What is distillation?
Distillation is one of the several physical methods that can be used to separate the substances in a mixture. it is used to separate a mixture of liquids that have dissolved into each other. the mixture is heated until one of the liquids evaporates. It’s vapours are then cooled and condensed to form separate liquids.
What is fractional distillation used for?
Fractional distillation is used to separate mixtures containing several different substances. it is used to separate crude oil into fractions in a continuous process.
Where does fractional distillation occur?
in a fractionating column
Explain the process of fractional distillation regarding crude oil.
- The oil is heated to evaporate it
- Vapour from oil rises up the column
- Each fraction condenses at a different temperature because it has a different range of boiling points
Name the properties that are linked with small molecule fractions.
lowest boiling points, least viscous, most flammable
Name the properties that are linked with large molecule fractions.
highest boiling point, most viscous, least flammable
What does combustion of a hydrocarbon do to its surroundings?
releases energy
What happens to hydrogen when complete combustion occurs?
the hydrogen is oxidised to produce water vapour
What happens to carbon when complete combustion occurs?
the carbon is oxidised to produce carbon dioxide
What happens if there isn’t enough oxygen in the air for complete combustion to occur?
It means it is incomplete combustion (partial combustion).
What happens when incomplete combustion occurs?
the hydrogen in the fuel is still oxidised and changed into water vapour (like complete combustion) but the carbon is not fully oxidised.
Because carbon is not fully oxidised when incomplete combustion occurs, what happens to it?
these products are formed:
- Carbon monoxide
- solid particles (which contains soot (carbon) and unburned fuel
How can sulfur dioxide pollution be reduced?
- removing sulfur from fuel
- removing sulfur dioxide after burning
What are biofuels made of?
produced from plant material rather than form fossil fuels
Name 2 advantages of using bioethanol and biodiesel.
- biodiesel can be used in diesel engines
- bioethanol can be mixed with petrol and used in petrol engines
Name a disadvantage of bioethanol and biodiesel.
farmland that could be used for food production is used for biofuel production instead.
What is the only product when hydrogen burned?
Water vapour
What are some advantages of using hydrogen as a fuel?
- No carbon dioxide is made.
- Hydrogen can be made by passing electricity through water.
Name some disadvantages of using hydrogen as a fuel.
- Most hydrogen is produced from fossil fuels at the moment.
- Electricity needed to make hydrogen from water may be generated by burning fossil fuels.
- Hydrogen is difficult to store and there are only a few places that sell it.
