Organic Chemistry Flashcards
(32 cards)
Describe the process of fractional distillation. (4 steps)
- Crude oil is heated.
- Long hydrocarbons remain as liquid at base of tower and tapped off in liquid form. (i.e bitumen)
- Shorter chains vaporize and rise up the tower.
- As the hydrocarbons reach their boiling point in the tower, they condense from gas to liquid and are tapped off.
Describe the process of cracking.
Large hydrocarbon molecules can be broken down into smaller molecules using a catalyst.
This is called cracking, and is an example of a thermal decomposition reaction.
Describe three processed fractions derived from fractional distillation.
Napththa (60-180C) - Making chemicals, especially plastics.
Paraffin/Kerosene (180-220C) - Aviation fuel for jet aircraft.
Diesel oil/gas oil (220-250C) - Fuel in diesel engines such as trucks.
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
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
Alkane General Formula
CnH2n+2
Alkene General Formula
CnH2n
Haloalkane General Formula
CnH2n+1 X
Isomers
Molecules that have the same molecular formula but a different structural formula.
What is Fractional Distillation?
Fractional distillation separates a mixture into a number of different parts, calledfractions.
A tall fractionating column is fitted above the mixture.
The column is hot at the bottom and cool at the top.
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 broke?
Weak dispersion forces are broken when the hydrocarbon reaches its boiling point and transitions from liquid to a gas.
The covalent bonds between the atoms do not break. 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 less dispersion forces between the molecules.
And therefore, less energy required to break them.
Outline the cracking process
The hydrocarbon molecules are heated until they turn into vapour, and then mixed with a catalyst.
Combustion (complete and incomplete)
Complete combustion hydrocarbon is burned in excess oxygen
hydrocarbon + oxygen → carbon dioxide + water
Incomplete combustion hydrocarbon is burned in limited oxygen
hydrocarbon + oxygen → carbon monoxide + water or
hydrocarbon + oxygen → carbon + water
Substitution reaction (with drawn example methane + chlorine –>)
One atom is swapped with another atom.
Alkanes undergo asubstitution reactionwithhalogensin the presence of light.
Addition reaction (ethene+bromine with conditions)
Double bond breaks and addition atoms are added.
Bromine water test (including equation, including conditions)
(type of addition reaction). A test to determine whether a solution contains alkanes or alkenes.
There is no change when bromine water is mixed with an alkane.
The bromine water goes from orange to colourless when it is mixed with an alkene.
Hydrogenation (addition reaction with H2, including conditions)
Alkene + hydrogen (150degreesC and Ni catalyst)→ alkane
Hydration (addition reaction with H2O, including conditions)
Alkene + water (steam) (catalyst + 300degrees C) → alcohol
