Challenge Problem #9
Name ____________________________
Due Monday, November 14, 2005, 5:00 pm. Room 121 Chemistry
Carminic acid, a naturally occurring red pigment extracted from the cochineal insect, contains
only carbon, hydrogen, and oxygen. It was commonly used as a dye in the first half of the
nineteenth century. It is 53.66% C and 4.09% H by mass. A titration required 18.02 mL of
0.0406 M NaOH to neutralize 0.3602 g carminic acid. Assuming that there is only one acidic
hydrogen per molecule, what is the molecular formula of carminic acid?