Answer:
Wood ashes are needed to supply the caustic potash ( potassium hydroxide ) needed for saponification to take place. And the PH of the water is basic because potassium hydroxide is a base.
Explanation:
Saponification is the process of soap making and another name for alkaline hydrolysis of fats and oils.
Vegetable oils or fat undergo hydrolysis:
I. Acid hydrolysis to yield fatty acids and alkanol.
Vegetable oil/fat + H2O (from acid) = Alkanoic acid ( fatty acid ) + alkanol
II. Alkaline hydrolysis to produce soaps and alkanol. Example:
Glyceryltristearate + caustic soda = Sodium stearate (soap) + glycerol.
Caustic soda ( NaOH ) is used to produce harder soaps while caustic potash ( KOH ) is used to produce softer soaps.
A solution of wood ash can be used instead of KOH for the production of softer soaps because it is rich in KOH.
