Organic chemistry Flashcards
What creature is crude oil from?
Crude oil comes from plankton which were buried in mud, and the remains after millions of years are plankton.
What are hydrocarbons made of?
Hydrogen and carbon only
What is the general formula for alkanes?
CnH2n+2
What are the four alkanes?
methane- 1 carbon atom
ethane- 2 carbon atoms
propane- 3 carbon atoms
butane-4 carbon atoms
Why do long chained hydrocarbons not make good feuls?
Because they aren’t very flammable not allowing it to combust.
What is cracking used for?
to break long chained hydrocarbons into smaller chained hydrocarbons.
What’s the difference between alkene and alkanes (in terms of structure)?
Alkenes have a double covalent bond between the carbon atoms but alkanes only have one covalent bond between the carbons.
How do you test for alkenes (due to their increased reactivity)?
You can use bromine water, once alkenes are placed inside it turns colourless.
What can alkenes be used for?
To make polymers and other useful chemicals
What are the two types of cracking?
There is steam cracking, which mixes the hydrocarbon with steam and heated to a very high temperature.
Catalytic cracking is when the hydrocarbon is passed over a hot catalyst.
Describe the process of fractional distillation.
Firstly, the crude oil is heated to a very high temperature, it is then passed through a tube which leads to a very tall tower, at the bottom it is very hot and at the top is it cooler. The evaporated crude oil liquidates once it reaches its boiling point and as it moves up to the cooler parts and reaches its boiling point, its taken through a certain tube which separates the shorter and longer hydrocarbons . Hydrocarbons with a very high boiling point will be taken through a seperate part of the tube at the bottom, hydrocarbons with a very little boiling point will leave the top as other gases.
What is viscosity?
The thickness of a substance, the more viscous the more thick.
What happens to the hydrocarbons as the chain gets longer (in terms of flammability)?
The hydrocarbons get less flammable as the chain increases.
What happens to the boiling point of a hydrocarbon as the size increases?
The boiling point increases as the hydrocarbon gets larger.
What happens during combustion of hydrocarbons in fuels?
The hydrogen and carbon are burned to release energy, as they burn they both react with oxygen (are oxidised). If the oxygen is unlimited then the hydrocarbon will undergo complete combustion where carbon dioxide and water is released.
