Carbon Chemistry Flashcards
What are hydrocarbons formed by?
Compounds formed from hydrogen and carbon atoms only.
What is the simplest type of hydrocarbon, and what is its formula?
Alkanes
CnH2n+2.
How many covalent atoms are formed from each carbon atoms in first four alkanes?
4.
What are the first four alkanes?
Methane, Ethane, Propane and Butane.
What does complete combustion of a hydrocarbon mean, and when does it occur?
Makes them into useful field? and releases a lot of energy.
Occurs when there is lots of oxygen.
Are carbon and hydrogen oxidized or reduced in combustion? (hydrocarbons)
Oxidised. ( gains oxygen)
What is crude oil? How long does it take to form?
Fossil fuel found in rocks.
These are natural substances and can be used as a source of energy.
Formed mainly from remains of plankton, that died millions of years ago and was buried in mud.
What can crude oil be used for?
Fuel for transport.
(Diesel oil, kerosene, heavy fuel oil, LPG)
Petrochemicals.
What is the series called that is formed from crude oil? And Why can crude oil form so many things?
Homologous series.
The carbon atoms can bond together to form different groups.
What changes the hydrocarbon properties?
How long the chain is, changes the properties.
What is the properties of the shorter hydrocarbon chain in crude oil?
More runny, less viscous.
Lower boiling point.
More flammable.
What can fractional distillation be used to separate?
Hydrocarbon fractions. (Mostly alkanes)
How does fractional distillation work?
Oil is heated until most has evaporated.
Gases enter a fractionating column and liquid is drained off.
In the column it’s hot as the bottom and gets cooler as you go up.
Shorter hydrocarbons have low boiling parts, and don’t condense and turn back into liquids until they move to the top of column.
Longer hydrocarbons drain out earlier on.
Fractional distillation -
What order does the fractions condense?
Bitumen at bottom.
Heavy fuel oil.
Diesel
Kerosene
Petroleum
LPG at top.
What does cracking mean?
Splitting up long chain hydrocarbons.
Why is cracking needed?
High demand for fuels with small molecules.
this is because short chain hydrocarbons tend to be more useful, so lots of longer alkane molecules are turned into smaller ones via cracking.
Cracking also make alkenes which are more reactive.
Name the two methods of cracking.
Steam cracking.
Catalytic cracking.
Explain steam cracking.
Long chain hydrocarbons are heated up to turn into gas.
Hydrocarbon vapor is mixed with steam, which is then heated to a very high temperature which splits them into smaller molecules.
Explain catalytic cracking.
Long chain hydrocarbons are heated to turn them into gas.
Then the vapor idnpsssed over a hot powdered aluminum oxide catalyst.
Long chain molecules split apart on surface of the specks of catalyst,
What type of reaction is cracking?
Thermal decomposition.
