Organic Chemistry Flashcards
What do hydrocarbons only contain?
They only contain hydrogen and carbon atoms
What bonds do alkanes have?
Alkanes have all C-C single bonds
What are the first four alkanes?
Methane, ethane, propane and butane
Hydrocarbon properties change as the chain gets longer
The shorter the carbon chain, the more runny a hydrocarbon is - less vicious
Shorter carbon chain are also more volatile - lower boiling points
Shorter the chain more flammable.
Complete combustion equation
Hydrocarbon + oxygen = Carbon Dioxide + water
How is crude oil made?
Crude oil, a fossil fuel, is made over a long period of time. Formed from remains of plants and animals that died millions of years ago that were buried in mud.
What can be used to separate hydrocarbon fractions?
Fractional distillation
How does fractional distillation work?
The oil is heated until most of it has turned into gas. The gases enter a fractionating column.
Describe the temperature gradient in a fractionating column used for fractional distillation.
Its hot at the bottom and gets cooler as you go up.
Describe longer hydrocarbons.
Have high boiling points. They condense back into liquids and drain out the column early on, when they’re near the bottom
Describe shorter hydrocarbons
Lower boiling points. They condense and drain out much later on, near to the top of the column where its cooler.
Name some uses of crude oil.
- oil provides the fuel for most modern day transport
- petrochemical industry use some hydrocarbons from crude oil as a feedstock to make new compounds for use in things like lubricants
What does cracking mean?
Means splitting long chain hydrocarbons. Breaking larger hydrocarbons into smaller ones
what are the conditions for cracking?
Catalyst + temperature
Explain the different methods of cracking.
Thermal decomposition - breaking molecules down by heating them.
Steam cracking - vaporise them, mix them with steam and then heat them to a very high temperature.
