Organic Chemistry Flashcards
(42 cards)
Homologous series
Compounds that have a similar chemical structure and chemical properties
Organic compounds
Compounds consisting of carbon atoms most commonly covalently bonded to hydrogen, nitrogen, phosphorus or oxygen atoms
Hydrocarbon
Organic compound containing only hydrogen and carbon.
Functional group
Specific groups of atoms within a compound that affect the properties of the compound.
Alkanes
Saturated molecules - all carbons to carbon single bonds
Alkenes
Unsaturated molecules - contains at least one carbon-to-carbon double bond
Test for unsaturation
Bromine water will turn brown/orange to colourless if at least one carbon-carbon double bond is present
Alkane General Formula
CnH2n+2
Alkene General Formula
CnH2n
Alkene functional group
Carbon-carbon double bond
Haloalkane General Formula
CnH2n+1X
Haloalkane functional group
Halogen X
Isomers
Molecules that have the same molecular formula but a different structural formula.
Fractional Distillation
Crude oil is heated to vaporise the contents.
A tall fractionating column is fitted above the mixture.
The column is hot at the bottom and cool at the top.
As HC reach their BP, they rise, condense from gas to liquid and are tapped off.
Short HC reach BP first.
Longer HC remain as a liquid and are tapped off in liquid form.
Why do the longer hydrocarbon chains take more heat energy to change state from solid to liquid or liquid to gas?
The longer the chain, the stronger the dispersion forces there are between the molecules thus requiring more energy to break.
Viscosity
Viscosityis a measure of a fluid’s resistance to flow.
When the hydrocarbon goes through a state change of liquid to gas, which bonds are broken?
Weak intermolecular forces (dispersion) are broken when the hydrocarbon reaches its boiling point and transitions from liquid to a gas. The covalent bonds between the atoms do not beak. This would required a higher amount of energy.
Difference in boiling point of small and larger hydrocarbons
Smaller the molecule the lower the boiling point because there are lesson intermolecular forces between the molecules.
And therefore, less energy required to break them.
Crude oil
A dark, viscous substance extracted from the ground
Hydrocarbons from short to long in crude oil and uses
Petroleum gas - heating and cooking
Gasoline - fuel for cars
Naphtha - plastic chemicals
Paraffin / Kerosene- fuel for planes
Diesel Oil - fuel in diesel engines e.g. trucks
Fuel Oil - home heating
Lubricating Oil - lubricants, waxes and polishes
Bitumen - road construction
How is crude oil bad for the environment and what are alternatives?
Extraction through drilling: disrput ecosystems and cause spillage
Refineries: Air and water pollution
Finite resource
Alt.: Plant-based biomass e.g. corn or tree bark
Cracking
Large hydrocarbon molecules can be broken down into smaller molecules using a catalyst.
Thermal decomposition
Cracking Method
Heating mineral wool soaked in oil with a catalyst. Catalyst is heated first because oil is flammable. Contents vapourise
Cracking Catalyst
Aluminium Oxide or Clay
