Differentiation of formaldehyde from other higher aldehydes

Chemicals needed

formaldehyde solution 1%  GSGESUND.gif (476 Byte) Xn    R 40-43    S 23-37

fuchsin sulphuric acid  GSGESUND.gif (476 Byte) Xi    R 36/37/38    S 26-36

propanal GSLEICHT.gif (932 Byte) F GSGESUND.gif (476 Byte) Xi   R 11-36/37/38     S (2)-9-16-29

hydrochloric acid 7%

One can also use other higher aldehydes.

Equipment needed

2 test tubes

Test procedure


The diluted mixtures can be discharged into the drainage.


to be possibly added


The color of formaldehyde (left) becomes more intense, that of propanal(right) pales.


derived from experiment 271, "Unterscheidung von Methanal (Formaldehyd) und Ethanal (Acetaldehyd)", p. 164, [1]