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Soluble in water soap - is a sodium or potassium salt
of saturated acid (most often, stearic).
In a test tube add about 1 g of soap and dissolve in
distilled water. Check the medium of the solution using a
universal indicator and phenolphthalein.
The resulting solution is divided into two test tubes
and added to a test tube a solution of sulfate acid. In this
case, a precipitate of insoluble saturated acids is released:

С 17Н 35СООNa+H 2SO 4 → С 17Н 35СООH+NaHSO 4
С 17Н 35СООNa+H 2SO 4 → С 17Н 35СООH+NaHSO 4

To another test tube with a solution of soap add a few
drops of 10 % solution of calcium chloride. Observe the
formation of insoluble precipitate of the calcium salt of the
acid:

2С 17Н 35СООNa+СaCl 2 →
2С 17Н 35СООNa+СaCl 2 → (С 17Н 35СОО) 2Ca+2NaCl
(С 17Н 35СОО) 2Ca+NaCl

Sample knowledge control card

1. Write the equation for the reactions of obtaining
compounds:
a) 2-methylpentanal from dihalogenalkane;
b) butanone from alkin;
c) chloroethanic acid from ethinium.
Specify the conditions for each synthesis.
2. Write the reaction interaction equation:
a) 2-propanone with KMnO 4;
b) 2-methylpentanal from [Ag (NH 3) 2] OH.