Properties of soaps

[Tanvir Ahmed Chowdhury]

1.    Soap dissolves very slowly in cold water but rapidly in hot water.

2. Soap dissolves in hot alcohol but is only carefully soluble in other organic solvents such as acetone, ether or petroleum.

3. In extremely dilute solutions soap ionizes as

      RCOONa ↔ RCOO‾+ Na+
                                             RCOO‾+ H2O ↔ RCOOH + OH‾   

4. Sometimes there are free fatty acid molecules in soap to form what is known as acid soaps. 
 


5. Soap reacts with hard water to form insoluble soap.
                                   

6. The no. of carbon atoms in the aliphatic chain of soap is very important.
      Less than 9(C) – No detergency power
      9-17(C) – Extremely good detergent
      Above 17(C) – Poor solubility

[shalauddin.ns]

chemistry knowledge is important to understand this.