Preparation of a Tenside

Wear protection glasses! – Be extremely careful with conc. sulfuric acid!

Prepare a water bath by filling a 250-ml-beaker half with water and heating it to ca.
80 [°C].
Weigh 0,5 [g] of cetyl alcohol and put it in a test-tube. Give ½ pipette of conc. sulfuric acid into another t.t. and 3 [ml] of dil. sodiumhydroxide solution into a third one.
Put all the t.t. into the water and allow to warm.
If the alcohol is molten add carefully 4 drops of sulfuric acid using a glass Pasteur pipette. After one minute add two drops of POP and then dropwise the sodium hydroxide. Shake carefully. When a weak but permanent pink colouration occurs the reaction is completed.
Finally fill the t.t. to 1/3 with distilled water and shake vigorously. A foam indicates the tenside.


For the following experiments distribute the content of the t.t. into 3 clean t.t.

Comparison of the properties of soap and tenside

Prepare a soap solution and fill 3 clean t.t. to the same extent as the other 3 t.t. containing the tenside.
Add to one soap and one tenside-t.t.:
a) Universal indicator paper
b) Dil. Hydrochloric acid
c) Calcium chloride solution

Observations? – Conclusions?