Alcohols -functional groups
Alcohols have an '-OH' functional group and end in '-ol':
Alcohol general formula: Cn H2n+1 OH.
1st alcohol: Methanol - CH3OH
2nd alcohol: Ethanol - C2H5OH
The 'OH' bit is the functional group.
Alcohols - Similarities and differences
1. Ethanol is soluble in water. Alkanes are insoluble in water.
2. Ethanol and water are both good solvents - lots of things dissolve in them.
3. The boiling point of ethanol is 78 degrees c. Thi is lower than the boiling point of water, but much higher than the boiling point of a similar size alkane.
4. Ethanol is a liquid at room temp, It evaporates easily and gives off fumes. Methane and Ethane are also volatile, but are gases at room temp. Water is a liquid at room temp, but not volatile.
Alcohols - Solvents and fuels
Alcohols are used as solvents and fuels and in manufacturing:
1. Alcohols such as methanol and ethanol can dissolve lots of compounds that water cannot e.g. hydrocarbons and oils. They are very useful in industry.
2. Methanol is also used in industry as a starting point for manufacturing other organic chemicals.
3. Ethanol is used in perfumesand aftershave lotions as it can mix with both oils (which give it smell) and water (which makes up the bulk)
4. Methylated spirit is ethanol with chemicals e.g. methanol added to it. It is used to clean things like paint brushes.
5. Alcohols burn in air to produce co2 and water because they contain hydrocarbon chains. Pure ethanol is clean burning so it is sometimes mixed with petrol and used as fuels for cars to conserve crude oil.
Alcohols - Reacting with sodium
Alcohols react with sodium:
1.Sodium metal reacts gently with ethanol, to produce sodium ethoxide and hydrogen -
sodium + ethanol --> sodium ethoxide + hydrogen
2. Sodium metal reacts much more vigorously with water - even melting because of the leat of the reaction -
sodium + water --> sodium hydroxide +hydrogen
3. Alkanes do not react with sodium at all.