Organic Chemistry Flashcards
Define: Hydrocarbon
Compounds that only contain Hydrogen and Carbon atoms only
Define: Saturated
Contain maximum number of hydrogen for given number of carbon
Define: Unsaturated
The presence of the double bond mean they don’t have as many hydrogen
Formula for Alkane
Cn H2n+2
Formula for Alkene
Cn H2n
Homologous series
Similar structural and Chemical properties, due to similar bonding
General Formula
Alkane/Alkene physical trends
1,2,3,4 - Carbon - Gasses
5,6,7,8 - Carbon - Liquids
Alkane Combustion
Burn in oxygen
Enough they will give carbon dioxide and water
Incomplete combustion
Not enough oxygen
Carbon monoxide/carbon (soot) produced instead of CO2
Why is CO poisonous?
Combines with haemoglobin instead of oxygen
Substitution reaction
Alkane is substituted by a different atom, like in the reaction with bromine
Test for C=C
Shake organic compound with bromine water and the orange water is decolourised. Same for gas, but bubble through the water
Alcohols
Contain a -OH group onto the carbon chain
Ethanol by Fermentation
Yeast is added to starch and left in warm (30-40*C)
Absence of air.
Enzymes convert sugar into ethanol and CO2
Ethanol by hydration of Ethene
Ethene is passed over steam with Phosphoric acid Catalyst
300*C, 60-70 atm. Unreacted material is recycled
Dehydration of ethanol to produce ethene
Ethanol is passed over hot aluminium catalyst
Pros/Cons of Hydration of Ethene
Pros - Fast and continuous process, Makes pure ethanol
Cons - High amounts of energy, Non-Renewable
Pros/Cons of Fermentation
Pros - Renewable, Doesn’t require much energy
Cons - Batch process is slow, Impure ethanol
Crude Oil
Finite, Mixture of hydrocarbons
Properties of Hydrocarbons
As chains increase: Boiling points increase
Liquids become less volatile
Liquids flow less easily
Bigger hydrocarbons burn less easily
Separating Crude oil
Oil is passed into a fractionating column, cooler at top than bottom. Boils, quickly then condenses at certain point to be tapped off
Crude oil column at top/at bottom
Top going down less volatile e.g refinery gasses most
Bottom going up less viscous e.g fuel oil
The 6 fractions
Bitumen, Fuel Oil
Diesel Oil, Kerosine
Gasoline, Refinery Gasses
Uses for Refinery gasses, Gasoline, Kerosine
Refinery Gasses - Domestic heating/cooking
Gasoline - Petrol
Kerosine - Aircraft fuel
Uses for Diesel oil, Fuel oil, Bitumen
Diesel oil - Busses, Lorries, some cars
Fuel oil - Ships boilers/industrial heating
Bitumen - Road making
Problems with fractions
Amounts depend on hydrocarbons
Unreactive make into reactive
Cracking
Large hydrocarbons are converted into smaller ones, that have more demand
How Cracking works
Fraction heated to give gas, then passed over silicon dioxide and aluminium oxide catalyst at 600-700*C. A mixture of single and double bonds could form.
Addition polymerisation
Double bond is broken and electrons are used to join neighbouring molecules
Polymerisation
The joining up of monomers to make polymers
Condensation reaction
When two monomers combine a small molecule is lost. The monomers retain their bonds.
