Question

Can someone explain why the pH of saponification turns out to be a strong base, I understand the process I just have to explain why the pH of my soap was 14, in atleast four sentences. Any explainations of the pH stages throughout the process of saponification would really be appreciated thank you in advance.

P.S. I used the heat process of making soap, and I used vegetable oil and NaOH

Answer 1

Oils and fats are glyceryl esters of higher fatty acids and soaps are Na or K salts of higher fatty acids.

Soaps are produced by the hydrolysis of oils and fats using an execess of alkali like NaOH.

Since soap is the product of this reaction, the alkaline hydrolysis of oils and fats is called saponification.

After hydrolysis the soap is salted out from the solution as a precipitate by adding NaCl .

If the soap thus prepared is not purified further by recrytallization it will contain lot of free unreacted alkali, NaOH

Hence the solution of the soap would be basic and pH would be greater than 7.

The actual pH value would depend on the amount of alkali present.

In the case of your soap, [OH-] = 1 M so that pOH = 0 and pH =14 (Remember pH + pOH =14)