Organic Chemistry Flashcards
How is crude oil made?
- Plants and algae die and are buried in mud
- Ancient remains are exposed to high pressures and temperatures
What are hydrocarbons?
Compounds of hydrogen and carbon only.
What makes alkanes a homologous series?
They are a family of compounds with similar chemical properties and the same general formula.
What is the alkane general formula?
CnH2n+2
Explain the process of fractional distillation.
- The crude oil is heated until it boils and entered into the fractionating column
- The column is hotter at the bottom and cooler at the top
- As the gases move up the column they condense when they reach their boiling point
What is the order in the fractionating column?
What are petrochemicals?
Useful substances and materials produced from crude oil.
E.g. Detergents, lubricants, polymers and solvents.
Give a reason why a huge number of different natural and synthetic carbon compounds are possible.
Carbon atoms can form a homologous series or families of similar compounds.
What happens to the boiling point, viscosity and flammability as the size of a hydrocarbon’s molecules increases.
Boiling point and viscosity INCREASE
Flammability DECREASES.
What is viscosity?
A measure of how easily it flows.
( High viscosity = very viscous = doesn’t flow easily)
What kind of reaction is combustion?
Oxidation
What is complete combustion?
Combustion in excess oxygen.
What is the equation for the complete combustion of a hydrocarbon?
Hydrocarbon + oxygen —> carbon dioxide + water
What is cracking?
A chemical process that breaks down hydrocarbons with large molecules to produce more useful substances with smaller molecules.
What is an alkene
They are a type of hydrocarbon that contain a carbon-carbon double bond.
Describe the different types of cracking.
Steam cracking:
- 750-900 •C
- Pressure in atmosphere = 2-4
- No catalyst
Catalytic cracking:
- 450-550 •C
- Pressure in atmosphere = 1
- Catalyst required
What are zeolites?
Substances that contain aluminium oxide.
What is the use in cracking?
To balance the supply of different hydrocarbons with the demand for them
(Fractional distillation produced too much of the larger hydrocarbons)
It produces alkenes which are a feedstock for making polymers
Why are alkenes more reactive than alkanes?
Their molecules contain c-c double bonds.
How can you test for alkenes?
Add bromine water to a test tube
Add stopper
Shake
Alkanes = No change
Alkenes = Orange-brown to colourless
What is the general equation for combustion?
Hydrocarbon + oxygen —> carbon dioxide + water
What are the names of the first four alkanes?
Methane, ethane, propane and butane
What is crude oil formed by?
The decomposition of plankton.
