1. Alcohols
Noadswood Science, 2013

2. Alcohols To understand the structure of alcohols
Wednesday, April 25, 2018
Alcohols
To understand the structure of alcohols

3. Alcohols
Alcohols have an –OH functional group, with the general formula
CnH2n+1OH
Methanol – CH3OH
Ethanol – C2H5OH
Propanol – C3H7OH

4. Alcohol Uses
Alcohols are flammable, burn to produce CO2 and H2O, are used as solvents / fuels
Ethanol is used for alcoholic drinks

5. Alcohol As Solvents
Alcohols such as methanol and ethanol can dissolve most compounds that water dissolves but they can also dissolve substances that water cannot, such as oils, fats and hydrocarbons
Ethanol is the solvent for perfumes and aftershaves (it can mix with the oils (giving the smell) and the water)
Methylated spirits (meths) is ethanol with other chemicals such as ethanol added to it – meths are used as pain cleaners and fuels (though they are poisonous to drink so are dyed)

6. Alcohol As Fuels
Ethanol is used as a fuel as it burns cleanly, and it can also be mixed with petrol (which reduces pollution)
Brazil have little oil, but lots of land to grow sugar cane for ethanol / petrol mix

7. Ethanol
Ethanol is the type of alcohol found in alcoholic drinks such as wine and beer
Ethanol is also useful as a fuel – for use in cars and other vehicles, it is usually mixed with petrol

8. Ethene + Steam  Ethanol
Ethanol can be manufactured by reacting ethene (from cracking crude oil) with steam –phosphoric acid is used as a catalyst: -
Ethene + Steam  Ethanol
C2H4+ H2O C2H5OH
In the reaction ethanol is the only product – the process is continuous as long as ethene and steam are fed into one end of the reaction vessel, ethanol will be produced
These features make it an efficient process, but as ethene is made from crude oil, which is a non-renewable resource, it cannot be replaced once it is used up and it will run out one day

9. Ethanol & Fermentation
Ethanol can also be made via fermentation – sugar from plant material is converted into ethanol and carbon dioxide…
Enzymes found in single-celled fungi (yeast) are the natural catalysts that can make this process happen (this is a renewable resource): -
C6H12O6  2C2H5OH + 2CO2
More than 90% of the world’s ethanol is made by fermentation