Organic Chemistry Flashcards
Saturated definition
Only single bonds in a molecule
Unsaturated definition
A molecule containing a double bond
Isomerism
- A group of compounds which share: • same functional group • same general formula • same chemical reactions • gradual change in physical properties
Hydrocarbon definition
A compound containing only carbon and hydrogen
Alkanes formula
Cn H2n+2
Uses of alkanes
Fuels
Order of alkanes
Methane, ethane, propane, butane, pentane
Complete combustion of alkanes
- A blue flame indicates complete combustion:
Methane + oxygen -> carbon dioxide + water
CH4 (g) + 2O2 -> CO2 + 2H2O
Incomplete combustion of alkanes
- when oxygen supply is limited, a yellow flame is produced so incomplete combustion occurs:
Methane + oxygen -> carbon + water
CH4 + O2 -> C + 2H2O
What else can be produced in incomplete combustion of Alkanes? (Fuels)
Carbon monoxide
Methane + oxygen-> carbon monoxide + water
2CH4 + 3O2 -> 2CO + 4H2O
Carbon monoxide is poisonous because it reduces the capacity of the blood to carry oxygen
A substitution reaction with alkanes
- methane with bromine, in the presence of UV light, a substitution reaction occurs:
Methane + bromine -> bromomethane + hydrogen bromide
CH4 + Br2 (g) -> CH3Br (g) + HBr
Alkenes formula
Cn H2n
Uses of alkenes
Making polymers
Order of alkenes
Ethene, propene, butene, pentene.
Additional reaction with alkenes
- alkenes react with bromine so the bromine water loses its colour
Ethene + bromine -> dibromoethane
(Colourless Gas)(orange Liquid)(colourless liquid)
What is in crude oil
Refinery gases - camping gas Gasoline - petrol Kerosene - fuel for planes Diesel - fuel for vans/lorries (diesel) Fuel oil - fuel for ships/heating systems Bitumen - tar on roads
How do the length of the molecules change in the fractional column and temperature
As you go up the column, the molecules get smaller
Increased length- increases boiling point
How does the viscosity change in the column
As the chain length increases, viscosity increases
Volatility definition
Volatility is the tendency of a substance to vapourise
What are the conditions for cracking
600-700° C
Silica or alumina catalyst
What could you use to test for alkenes
Bromine water (turns from brown -> colourless)
General characteristics of any homologous series
- different physical properties
- presented by the same general formula
- same chemical characteristics
Manufacture of ethanol
- passing ethene and steam over a phosphoric acid catalyst
- temperature of 300° C
- pressure of 60-70 atm
Fermentation
- sugar is converted to ethanol using yeast (enzyme is zymase)
- requires 30° C
Dehydrating ethanol
C2H5OH —> C2H4 + H2O
- ceramic wool soaked in ethanol
- aluminium oxide catalyst
Making ethanol from Ethene, advantages and disadvantages
Advantages
- fast continuous process
- Large amounts of ethanol produced
Disadvantages
- uses nonrenewable resources
- flavours have to be added artificially
Making ethanol from Fermentation, advantages and disadvantages
Advantages
- uses renewable resources
- produces flavour of alcoholic drinks
Disadvantages
- slow ‘batch’ process
- only small amounts of ethanol produced
- what produced isn’t pure
Polymerisation
- The joining up of lots of little molecules, called monomers, to form a big molecule called a polymer
2 types of polymerisation
Additional polymerisation
Condensation polymerisation
Addition polymerisation
When alkenes add together to form the polymer
E.g. styrene —> polystyrene
Condensation polymerisation
- requires two different monomers
- The monomers react together and bonds form
- with each new bond formed, small molecule is lost e.g. a water molecule (condensation)
E.g nylon
Uses of polymers
Polyethene- light, waterproof, for plastic bags
Polypropene- heat resistant, kettles
Polychloroethene- water pipes, insulation on electrical cables
What is a monomer
A molecule that can combine with others to form a polymer
What is a polymer
A large molecule made up of linked monomers
Draw the repeat unit of addition polymers
- poly(ethene)
- poly(propene)
- poly(chloroethene)
Why are addition polymers hard to dispose of
Because of their inertness means they do not easily biodegrade
What is a homologous series
A group of organic compounds with the same general formula, similar chemical properties and physical properties that change gradually from one member of the series to the next
What is a general formula
It is a type of empirical formula that represents the composition of any member of an entire class of compounds.
What do cars produce which contribute to acid rain
Nitrogen oxide
