Intro to Organic Chem Flashcards
How is petroleum separated into fractions?
Fractional distillation, fractions of petroleum have different boiling points.
Why is petroleum separated into fractions?
Before separation, petroleum contains large mixture of hydrocarbons of varying lengths. Thus, it will be less efficient fuel, resulting in sootier and smokier flame when burnt due to incomplete combustion (C, CO, CO2)
Steps of fractional distillation of petroleum
- The petroleum is first heated into vapour.
- The vapour passed up the fractioning column.
- The fractions condense out of different heights depending on their boiling points.
- Lighter fractions contain molecules with lower molecular masses, hence less dense and have lower boiling point. They will come out as fractions near the top of the column. Heavier fractions contain molecules with higher molecular mass hence denser and have higher boiling point will come out as fractions near the bottom of the column.
Fractions in petroleum
Petroleum gas Petrol/ Gasoline Naphtha Kerosene/Paraffin Diesel Lubricating oil Bitumen
Use of petroleum gas
Fuel for cooking and heating
Use of petrol/gasoline
Fuel for car engines
Naphtha
Used as chemical feedstock for chemical industry
Kerosene/Paraffin
Fuel for aircraft engine
Fuel for domestic cooking and heating
Diesel
Fuel for diesel engines in buses, lorries and trains
Use of lubricating oil
As lubricants for machines and as sources of waxes and polishes
Use of bitumen
For making road surfaces
Issues with use of petroleum
- Pollution and global warming
2. Petroleum is non-renewable and finite, resulting in competing use.
Ways to conserve petroleum
- Reduce the use of petroleum
- reducing the number of vehicles on the road
- drive smaller cars that consume less petrol
- take public transport instead - Use alternative energy sources
- solar energy
- nuclear energy
- Biofuel - Improve design of power stations and vehicles so that they use petroleum more efficient
Definition of hydrocarbons
Hydrocarbons are organic compounds that contain hydrogen and carbon only.
Definition of homologous series
A family of organic compounds with the same functional group and similar chemical properties
Definition of functional group
An atom or a group of atoms that give a molecule its characteristic chemical properties
Characteristics of organic compounds in the same homologous series
- Same general formula
- Similar chemical properties (as they have the same functional group)
- Differ from the successive member by a -CH2 group
- Gradual change in their physical properties
Melting and boiling point increases down the group.
As their molecular sizes increases, the number of electrons increases, the intermolecular forces of attraction is stronger, a higher amount of energy is required to overcome the stronger intermolecular forces of attraction hence melting and boiling point increases.
Increase in viscosity
Molecular sizes increases, the number of electrons increases, stronger intermolecular forces of attraction hence flow less easily.
Flammability decreases
As their molecular sizes increases, the number of electrons increases, the intermolecular forces of attraction is stronger, a higher amount of energy is required to overcome the stronger intermolecular forces of attraction hence boiling point increases, thus, less volatile and less flammable.
Prefix
Denotes substituents/ side groups
Parent
Denotes largest continuous carbon chain bearing as the principal functional group
Suffix
Denotes principal functional group
