Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Acetone and Polystyrene Foam
Name: Holly Rippee
Status: student
Age: 14
Location: N/A
Country: N/A
Date: Around 1999

When you place a foam cup in acetone, the cup melts. My question is why? I know that the acetone is taking the air out of the cup, but how?

The foam cup is made out of polystyrene foam, which is a foam of poly styrene. This means that there is a chemical styrene which is made into a plastic. Its like jello. Styrene is the jello mix you pour into the bowl. When you put the jello into the refrigerator, the jello turns thick. This is like the styrene turning into polystyrene. Now somebody comes along and takes this thick hard stuff, polystyrene and pushs it into the shape of a cup. (You can make the jello take the shape of a mold too, maybe some fancy cup, or funny shapes to eat).

So now you have this polystyrene cup. But if you come along now and pour on acetone, it breaks down the connections between the strands of polystyrene. The cup dissolves.

OK, its not exactly the same thing but if you made a cup out of jello and then poured in hot water, the jello would dissolve in the hot water. The cup would fall apart. Its too small for you to see, but little blobs of water are getting in between the globs of jello, dissolving it, and ruining the cup.

S. Ross

Actually, the acetone is dissolving the plastic in the cup, and the blow gas inthe foam is just escaping into the air. It's exactly the same type of process as when you put popcorn into water.

Richard Barrans Jr., Ph.D.
Chemical Separations Group
Argonne National Laboratory

Click here to return to the Chemistry Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory