Topic 7 - Organic Chemistry Flashcards
What is a hydrocarbon
Any that is formed from carbon and hydrogen atoms only
What is the formula for alkanes
CnH2n+2
What is the homologous series
A group of organic compounds that react in a similar
What are alkanes ( 3 points)
-The simplest type of hydrocarbon you can get
-Saturated compounds (each carbon atoms forms four single covalent)
-They are a homologous series
What are the first four alkanes
Methane, ethane, propane and butane
How does the length of the carbon affect how runny it is
The shorter the chain the more runny it is (less viscous)
How does the length of a carbon chain affect how volatile it is
The shorter the chain the more volatile, so it will have a lower boiling point
How does the length of a carbon chain affect how flammable it is
The shorter the chain the more flammable the hydrocarbon is
What are short chain hydrocarbons used for in fuel and why
As they have lower boiling points they are used as ‘bottled gases’ - stored under pressure as liquids in bottles
What does the complete combustion of any hydrocarbon in oxygen release
Lots of energy
What waste products are formed from the complete combustion of any hydrocarbon in oxygen
Carbon dioxide and water vapour
Write the equation of complete combustion of any hydrocarbon in oxygen
hydrocarbon + oxygen > carbon dioxide + water (+energy)
During combustion what happens to both the hydrogen and carbon from the hydrocarbon
They are oxidised
Why are hydrocarbons used as fuels
-Due to the amount of energy released when they combust completely
What is crude oil
A fossil fuel
How is crude oil formed
-From the remains of plants and animals, mainly plankton that died millions of years ago and were buried in mud
-Over millions of years high temperature and pressure turns the remains to crude oil which can drilled up from the rocks where it’s found
What is the problem with crude oil being a fossil fuel
Like coal, oil and gas it is non-renewable fuels as they so long to make that they’re being used up much faster than they’re being formed so they’re finite resources
Why does crude oil have to be separated by fractional distillation
As it is a mixture of lots of different hydrocarbons, most of which are alkanes the different compounds have to be sepersted
How does fractional distillation work
- The oil heated until most of it has turned to gas which enters a fractioning column (and the liquid bit is drained off)
- In the column there’s a temperature gradients (hot at bottom cooler as it goes up)
- Longer carbons have high boiling points so condense into liquids and drain out of the column early on, near the bottom. The shorter hydrocarbons gave lower boiling points and condense and drain out much later near the top of the column
- You end up with the crude oil mixture separated out into different fractions, and each contains a mixture of hydrocarbons that all contain a similar number of carbon atoms, so have similar boiling points
What is the order of fuels that condense in the fractioning column from earliest to latest
Bitumen
Heavy fuel oil
Diesel oil
Kerosene
Petrol
Liquefied Petroleum Gas
Approximately how many carbon atoms are in LPG
3
Approximately how many carbon atoms are in Petrol
8
Approximately how many carbon atoms are in kerosene
15
Approximately how many carbon atoms are in diesel oil
20
Approximately how many carbon atoms are in heavy fuel oil
40
What is feedstock
A feedstock is a raw material used to provide reactants for an industrial reaction
What feedstock are hydrocarbons from crude oil used for
They make new compounds in things such as:
-polymers
-solvents
-lubricants
What are organic compounds
Compounds containing carbon atoms
Why do you get a large variety of products made from crude oil
Carbon can bond to form different groups called homologous series which contain similar compounds with many properties in common
What can heavy fuel oil be (3)
-Heating oil
-Lubricating oil
-Fuel oil
Why do short-chain carbons make good fuels
They are flammable
What happens to less useful long chain hydrocarbons
They are turned into smaller, more useful hydrocarbons through a process called cracking