Physical properties of alcohol can be explained by following points –
Alcohols are colourless.
They generally give a sweet smell except glycerol and few lower alcohols.
They are flammable and produce blue flame.
They don’t produce any smoke while burning.
They are generally liquid at room temperature. Although glycerol is viscous liquid.
Boiling Point of Alcohol - They generally have higher boiling points if we compare with other hydrocarbons. For example, ethanol shows boiling point 78.29℃ while hexane shows boiling point 69℃. This is because of presence of intermolecular hydrogen bonding between hydroxyl groups of alcohols. Boiling point of alcohols increases with increasing number of carbon atoms in organic alcoholic compounds.
Alcohols work as suitable solvent for many organic compounds. As organic compounds are insoluble in water.
Alcohols are acidic in nature. They react with metals such as sodium, potassium etc. It is due to the polarity of bond between hydrogen atom and oxygen atom of hydroxyl group. Primary alcohols are more acidic than secondary and tertiary alcohols.
Due to polar -OH bond in alcohols, they are more soluble in water than other simple hydrocarbons. For example, methanol and ethanol are miscible in water.
Chemical properties of alcohol can be explained by following points –
Oxidation Reaction of Alcohol – Alcohols produce aldehydes and ketones on oxidation. Reaction is given below –
C2H5OH + 2[O] 🡪 CH3COOH + H2O
Ethanol Methanoic acid
Combustion of Alcohol – On heating ethanol gives carbon dioxide and water and burns with blue flame. Reaction given below –
C2H5OH + 3O2 🡪 2CO2 + 3H2O
Dehydration of Alcohol – Alcohols can be dehydrated in acidic medium. Removal of water molecules from a compound is called dehydration. Upon dehydration alcohols, give alkenes. Reaction is given below –
Reaction of Alcohol With Metal – Due to their acidic nature alcohol reacts with metal and forms alkoxide. For example, when ethanol reacts with sodium forms sodium ethoxide and hydrogen gas. Reaction is given below –
Formation of Halides From Alcohols – Alcohol reacts with HCl and forms alkyl halides by removal of hydroxyl groups. reaction is given below –
ROH + Zn + HCl 🡪 R-Cl
Esterification – Alcohol reacts with carboxylic acid in presence of catalyst and forms ester. It is called Fischer esterification. Reaction is given below –
This was the brief on physical and chemical properties of alcohols, if you want to get detailed study notes on the topic alcohols then register yourself on Vedantu or down Vedantu learning app for Class 6-10, IIT-JEE and NEET.