Topic 7 - Organic Chemistry Flashcards
What is a hydrocarbon?
A molecule that is formed only from hydrogen and carbon
What are the first four alkanes?
Methane
Ethane
Propane
Butane
What is the formula for alkanes?
CnH2n+2
What are saturated compounds?
Each carbon atom has four single bonds, no double bonds
What are the properties of alkanes as chin size increases?
Boiling point increases
Volatility decreases due to high boiling point
Flammability decreases
Viscosity increases
What is the formula for complete combustion?
Hydrocarbon + oxygen -> Co2 + water
What is fractional distillation?
The process of separating crude oil into its hydrocarbon components
How is crude oil made?
Plankton that died millions of years ago and got buried.
They got turned into crude oil by high temperatures and pressures
They can be drilled out of the rock
What are the key features of fractional distillation?
A fractional column that is cooler toward the top.
Hydrocarbons will condense into a liquid a certain points when the become cooler than there boiling points
What is cracking?
Cracking is a thermal decomposition reaction which uses heat to break down hydrocarbons
What are the two types of cracking?
Steam cracking
Catalytic cracking
What are the steps to catalytic cracking?
Vaporise the alkanes
Pass over aluminium oxide powder
This causes them to split apart
What are the steps of steam cracking?
Vaporised alkanes
Mix with steam
Heat to high temp so alkanes are split
What is an alkene?
An hydrocarbon with a double bonded carbon
What is the formula for alkenes?
CnH2n
What forms during cracking?
An alkane and an alkene
Are alkenes saturated or unsaturated and why?
Unsaturated because they contain two fewer hydrogen atoms than the alkane with the same number of carbon atoms.
What are the difference between alkanes and alkenes?
Alkenes are more reactive so when added to bromine water it will turn from orange to colourless
Alkenes can be added together to form polymers by breaking their double bond
What is the test for alkenes?
Adding them to bromine water should turn it colourless