Fuels and hydrocarbons Flashcards
What is the definition of a hydrocarbon?
A substance that contains ONLY hydrogen and carbon
What is the general formula for alkanes
CnH2n+2
What is the general formula for alkenes
CnH2n
What are fractions?
Different substances we get from distilling crude oil
How are hydrocarbons in crude oil bound?
A ring
What are the 2 main ways to dispose of polymers
Landfill + combustion
What does incomplete combustion create?
Carbon, which then can form carbon monoxide
What does complete combustion of alkanes always create?
ONLY water and carbon dioxide
Heat for cracking?
600-700°C
Catalyst used for cracking?
Aluminium or silica oxide
What does poly- added before an alkene mean?
It is the repeat unit
What will happen when you add ALKENES to bromine water?
Bromine water will turn from orange to colourless
What will happen when you add ALKANES to bromine water?
The bromine water WILL NOT CHANGE COLOUR
What is the definition of cracking?
The process of breaking down longer-chain hydrocarbons into shorter-chain alkanes and alkenes
What are 2 features of the same homologous group?
- Similar chemical properties
- Same functional group
What type of reaction is cracking?
Cracking is a thermal decomposition reaction
What is crude oil?
A complex mixture of hydrocarbons
Is the top of an oil fractionating column hotter or cooler than the bottom of an oil fractionating column?
The top is cooler than the bottom of the column
What happens to a liquid during its separation from a mixture by distillation?
It evaporates and then condenses
In comparison to large hydrocarbons, what are the properties of small hydrocarbons?
They are more volatile, flammable and have a lower boiling point
What is really the only reactions for hydrocarbons?
Combustion
What is a liquid fossil fuel (like crude oil) formed from?
The remains of microscopic dead plants and animals that lived in the sea.
What does volatile mean?
A substance boils easily
Are ALKANES saturated or unsaturated?
They are saturated
Are ALKENES saturated or unsaturated?
They are unsaturated
Where are the most viscous hydrocarbons likely to leave the fractionating column at?
The bottom
What is the name by which we separate crude oil into useful components?
Fractional distillation
What are the products of cracking?
Alkanes and alkenes
What is polymerisation?
When many small alkene molecules (monomers) join together to form polymers
