Organic Chemistry Flashcards
To learn organic chemistry
Describe the purpose of fuels
Fuels release energy when they combust (burn) in oxygen. This energy released can be used to do work; for example, power a car.
What are the three most important type of fuels. Describe the primary chemical composition of each of them.
- Coal is mainly carbon
- Natural gas is mainly methane.
- Petroleum is primarily a mixture of hydrocarbons
What are fossil fuels?
Sources of energy (fuels) that are formed over many years from dead plants and animals.
What does non-renewable fuels mean?
That once they have been used, would run out.
When fuels are burned, a gas is released. Name it.
This gas also affects that environment in some way, how does it do so?
Carbon dioxide is released from the compete combustion of fuels in air. It is a green house gas and is said to be a cause of climate change.
What are Hydrocarbons?
are molecules containing only hydrogen and carbon atoms.
Which method of separation is used to separate petroleum into hydrocarbons.
Fractional Distillation.
In the fractional distillation of Petroleum, fractions are formed. name the eight of them, and
- Refinery gases : bottled and used for home and cooking.
- Gasoline: petrol for cars.
- Naphtha: making chemicals.
- Kerosene/paraffin: jet fuel.
- Diesel oil/gas oil: diesel engine fuel for buses and lorries.
- Lubricating oil: lubricants, waxes and polishes.
- Bitumen: making road surfaces.
Describe the process of fractional distillation of Petroleum. Describe the state of each fraction and how it is collected.
- Petroleum is heated to 350 degrees and enters the fractionating column. The hydrocarbons separate into fractions with similar boiling points.
- The fractionating column is coolest at the top. fractions with the lowest boiling points travel up the column before condensing.
- Hydrocarbons with smallest molecules rise to the top and stay as gases.(Propane and Butane)
- The largest molecules of petroleum separate as solids and are drawn off at the bottom of the column. This is known as the bitumen fraction
What is the trend seen, going up the fractionating column? [4]
- They have fewer carbon atoms.
- Are less viscous (sticky) and flow more easily.
- Have lower boiling points.
- Are more flammable (ignite more easily)
what is cracking?
It is the breakdown of larger hydrocarbon molecules into smaller hydrocarbon molecules.
What are the properties of the lower fractions (bitumen fraction) that make them less useful than those at the top of the column.
- Too viscous (sticky)
2. Do not catch fire easily; limits different purposes that it ca be used for.
How is cracking carried out?
Usually, by heating the hydrocarbon with a catalyst.
For example, Decane - heat/ catalyst > octane + ethane.
[The hydrocarbons can break anywhere and smaller hydrocarbons can be produced, too]
During cracking, a gas is released that is used for to manufacture ammonia in the Haber process. Name it.
Hydrogen.
What is a fraction?
A collection of hydrocarbon compounds that have similar properties and boiling points. They distill off at the same position in the fractionating column.
what are saturated hydrocarbons?
are molecules made up of hydrogen and carbon atoms only, where all the carbons atoms in the molecule are bonded with only single bonds.
What is a homologous series?
- are a family of similar compounds, with similar chemical properties, due to the presence of the same functional group.
- The compounds in a homologous series have the same general formula and each member differs from the next by a CH2 group.
- There is a gradual change in the physical properties as the number of carbon atoms increase.
What are functional groups?
are the atoms or group of atoms, responsible for the characteristic reactions of a molecule.
What are Alkanes?
They are:
- saturated hydrocarbons.
- are a homologous series.
- Do not have functional groups. They only have C-C and H-H bonds.
Name the alkanes containing 1-4 carbon atoms
- Methane: CH4
- Ethane: C2H6
- Propane: C3H8
- Butane: C4H10
[Remember structural formulas and now how to draw all of them, showing the covalent bonds]
What is the general formula of Alkanes?
CnH(2n+2)
There is a gradual change in the physical properties of compounds in the homologous series. One of which is their melting point that increases as the number of carbon atoms increase. Why is this?
Due to an increase in the relative molecular mass,Mr and the length of the molecules.
Why do all Alkanes have similar chemical properties?
They all have similar C-H and C-C bonds.