Demonstration of phenolphthalein

Chemicals needed

distilled water

acetone GSLEICHT.gif (932 Byte) F   R 11    S (2)-9-16-23-33

sodium hydroxide solution 7,5%  GSATZEND.gif (935 Byte) C    R 35     S (1/2)-26-37/39-45

phenol GSATZEND.gif (935 Byte) C GSGiftig.gif (734 Byte) T     R 24/25-34    S (1/2)-28-45

phthalic anhydride GSGESUND.gif (476 Byte) Xn   R 22-37/38-41-42/43    S (2)-23-24/25-26-37/39-46

sulphuric acid 96%  GSATZEND.gif (935 Byte) C    R 35   S (1/2)-26-30-45

Equipment needed

2 test tubes
alcohol burner

Test procedure



Out of one molecule of phthalic anhydride and two molecules of phenol phenolphthalein together with water discharge results.

phenolphtalein.gif (2019 Byte)



DSCN0571.JPG (182417 Byte) phph2.jpg (2151 Byte)

The reaction mixture at the beginning(left) and at the end(right) of heating.

 phph4.jpg (4504 Byte)

The typical coloration with phenolphthalein


Derived from experiment 20511 S, "Phenolphthalein", p. 335, [2],
where instead of concentrated sulphuric acid anhydrous zinc chloride is used.