Give an example of a reaction of fatty acids with alkalis?

When fatty acids react with alkalis the result is the
formation of soap. Soaps can be made from both fatty acids derived from plants as well
as fatty acids derived from animals. The type of fatty acid and alkali used determines
the nature of the soap.

Soaps made with vegetable oils like
olive oil are soft, coconut oil leads to the production of a lot of lather. Animal fats
are generally not used in soaps meant to clean the
body.

The metal forming the alkali influences soaps in a
similar way.  Sodium soaps are hard while potassium soaps are soft and are usually what
liquid soaps are made of. Where the soap is to be used for harsh applications lithium is
used.