Question

Write the chemical equation for fot the reaction between mgcl2 and the soap you preapred

Answer 1

Soap is the sodium or potassium salt of long chain of fatty acid. Fatty acids when treated with NaOH or KOH forms Soap. This process is called as Saponification. Examples of Soap are as follow,

                                     1.  Sodium Stearate C₁₇H₃₅COONa
                                   
                                     2.  Potassium Oleate C₁₇H₃₃COOK

Reaction of Soap with MgCl₂;

When Soap is treated with MgCl₂ or CaCl₂ it forms insoluble precipitate called S.C.U.M. The reactions with MgCl₂ are as follow,

                2C₁₇H₃₅COONa + MgCl₂  -------->  2C₁₇H₃₅COOMg  + 2 NaCl

                2C₁₇H₃₃COOK   + MgCl₂  -------->  2C₁₇H₃₅COOMg  + 2 KCl

These reaction are often found in hard water. And this reaction decreases the effectiveness of soap.