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Name: Bill Unwin
Status: student
Age: 7
Location: N/A
Country: N/A
Date: Around 1999

What is the chemistry of aspirin? What does C9H8O4 mean?

Dear Bill,

First of all, make sure that you work together with a grownup before experimenting with any chemicals. I am a chemist, and real chemists NEVER WORK ALONE.

Aspirin is the common name of the chemical chemists know as salicylic acid. If it is dissolved in water the solution will be acidic (just like vinegar and lemon juice are acidic). Aspirin is a weak acid, though, so unless a lot of aspirin is dissolved it will not be nearly as strong an acid as those.

C9H8O4 is a formula which tells how many atoms are in each molecule of salicylic acid. So there are 9 C (carbon) atoms, 8 H (hydrogen) atoms, and 4 O (oxygen) atoms.

I hope this helps.

Best wishes,

Prof. Topper
Dept of Chemistry
The Cooper Union
New York, NY


Aspirin is really a nickname for acetylsalicylic acid. The C9H8O4 is the chemical formula for aspirin, which is a type of short cut to tell what it is made of. C stands for carbon, H stands for hydrogen and O stands for oxygen. So, C9H8O4 means that each aspirin molecule is made up of 9 carbon atoms, 8 hydrogen atoms and 4 oxygen atoms.

These atoms are actually in a very cool arrangement. Six of the carbons link together to form a ring, with the other atoms hanging off the sides.

The shape and the electrical charges of the molecule give it the ability to stop fever and pain in the body.

Laura Hungerford, DVM, MPH, PhD
University of Nebraska

C9H8O4 tells the number and type of atoms in a molecule of aspirin. In this case, it means 9 carbon, 8 hydrogen and 4 oxygen. This does not completely specify what a molecule of aspirin is, as other molecules can contain the same number and types of atoms in different arrangements.

As far as what the "chemistry" of aspirin is, well, I'm not quilified to completely explain all its effects in the body, etc. If you have a specific question about some particular type of effect it has or reaction it might undergo, that will be easier to answer than a general question about chemistry. There is so much that could be said about the chemistry of aspirin (or any other compound, for that matter) that I really don't know where to begin.

Richard E. Barrans Jr., Ph. D.
Chemistry Division
Argonne National Laboratory

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