C14. Organic chemistry Flashcards
What do all organic compounds contain?
Carbon
Usually hydrogen as well.
What types of fossil fuels product carbon dioxide on combustion?
Coal, natural gas and petroleum.
What process separates petroleum into different fractions?
Fractional distillation.
What is the main constituent of gas?
Methane
What does petroleum consist of?
A mixture of hydrocarbons - carbon and hydrogen atoms.
How does fractional distillation work?
Separates the hydrocarbons using the difference in their boiling points.
State the trends of petroleum distillation.
- Down = the boiling points increase (temp increases)
- Down = the size of molecules is larger.
- Down = density increases.
- Down = flammability increases.
State the use and temperature range of ‘refinery gas’.
Bottled as gas for heating and cooking.
Under 40C.
State the use and temperature range of ‘gasoline’ (petrol).
Fuel for cars (petrol).
40 - 100C.
State the use and temperature range of ‘naphtha’.
Making chemicals, especially plastics.
80 - 180C.
State the use and temperature range of ‘kerosene’ (paraffin).
Fuel for jet aircraft and heating.
160 - 250C.
State the use and temperature range of ‘diesel oil’.
Fuel for lorries and tractors.
250 - 300C.
State the use and temperature range of ‘fuel oil’
Fuel for power stations, ships and home heating.
350 - 500C
State the components and the uses of ‘residue’.
Lubricating oil - lubricants, waxes and polishes.
Bitumen - making road surfaces and sealing roofs.
Name the characteristics of ‘alkanes’.
- Hydrocarbons
- Compounds of carbon and hydrogen only
- Single bonds (saturated)
- E.g. Methane, Ethane, Propane, Butane
- Not very reactive but they burn well
- Ends in -ane
Name the characteristics of ‘alkenes’.
- Hydrocarbons
- Carbon and hydrogen only
- Have a double bond between two of the carbons (unsaturated)
- E.g. Ethene, Propene etc.
- Ends in -ene
Name the characteristics of ‘alchohol’.
- Like alkanes
- One of the hydrogen atoms is replaced by OH
- E.g. Ethanol
- Ends in -ol
What is a homologous series?
A group of compounds with the same functional group.
- Similar properties
What is the formula for ‘alkanes’?
C(n)H(2n+2)
What is the formula for ‘alkenes’?
C(n)H(2n)
What is the formula for ‘alcohols’?
C(n)H(2n-1)OH
What is the formula for ‘acids’?
C(n)H(2n-1)COOH
What are the differences between homologous series?
- Chain length
- Physical properties gradually change due to increasing molecule size
How do we form ethanol?
Fermentation - enzymes in yeast cells break down glucose to carbon dioxide and ethanol (exothermic)
From alkenes by addition of steam
C(6)H(12)O(6) -> 2C(2)H(5)OH + 2CO(2)
What is another way of obtaining ethanol in a chemical factory?
Addition of the catalyst steam to ethene.
Describe the combustion of ethanol.
Burns in oxygen to form carbon dioxide and water.
C(2)H(5)OH + 3O(2) -> 3H(2)O + 2CO(2)
What the uses of ethanol?
As a fuel + solvent (dissolves many things and evaporates easily)
Why is ethanol a better fuel than petrol?
It has already has an oxygen molecule in it.
How do manufacture alkene?
Alkanes -> alkenes
- Heat alkane in the presence of a catalyst -> molecule breaks down
