Organic chemistry Flashcards
What is a hydrocarbon
A molecule made up of hydrogen and carbon atoms only
What is an alkane
A hydrocarbon with the formula CxH(2x+2)
Why are alkanes a homologous series
They react in a similar way
Whay are alkanes saturated
They dont have any double bonds
What are the first four alkanes
Methane
Ethane
Propane
Butane
What happens to viscosity as hydrocarbon chain length increases
As chain length increases, Viscosity (gloopiness) increases
What happens to volatility as hydrocarbon chain length increases
Volatility decreases as hydrocarbon chain length increases
What happens to Flammability as hydrocarbon chain length increases
The longer the hydrocarbon is, the less flamable it is
What happens to boiling as hydrocarbon chain length increases
The longer the hydrocarbon is, the higher the boiling point is
When does complete combustion occur
When there is sufficient oxygen
What is the formula for complete combustion
Hydrocarbon + Water –> Caarbon dioxide + Water
What happens to carbon and hydrogen during conplete combustion
They are both oxidised
Is combustion endothermic or exothermic
Exothermic as it releases energy
What is crude oil
A fossil fuel formed by the remains of animals and plants
How do you get fossils fuels
BY drilling into the earth and extracting them
Where does crude oil go to get seperated into different fractions and what is the process called
Fractionating column in a process called fractional distillation
Explain how fractional distillation works
The column is hottest at the bottom and coolest at the top
The short chains evaporate and go to the top where it is coolest, where they then condense and can be extracted at the top of the column as liquids.
The long chains do not evaporate and stay liquid at the bottom of the column to be taken out.
What are some uses of crude oil (3)
Fuels, Polymers and Lubricants
What is cracking
Splitting up longer chain molecules into short chains so they can be more useful for things like fuels
What are the two types of cracking and what type of reaction is cracking
There is themal cracking and catalytic cracking
They are both thermal decomposition reactions
Explain catalytic cracking
Ensure to mention the temperature
Heat the long chain hydrocarbons until they are vaporised
Have some aluminium oxide ready as the catalyst
Pass the vaporised hydrocarbon along the aluminium oxide
It is done at 500 degrees
Explain thermal cracking
Ensure to mention the temperature and pressure
The crude oil is vaporised
It is then mixed with steam and heated at a high temperature and high pressure
The Hydrocarbon will crack
It is done at 750 degrees at 70 ATM
What is an alkene
A hydrocarbon with the general formula CxH2x
Why are alkenes unsaturated
They are unsaturated because they have a double bond between the Carbons
