The reaction that takes place inside the pumpkin uses calcium carbide to generate a very small amount of acetylene gas. When the gas is ignited, a tremendous amount of energy is released, which pushes the pieces of previously carved pumpkin out. Acetylene gas is very explosive. Mixtures with air containing between 3% and 82% acetylene are explosive on ignition.

The above is from: http://www.stevespanglerscience.com/experiment/exploding-pumpkin

It is just an explosive way to try to spark students interests in chemistry.

From: DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**MED.CORNELL.EDU] On Behalf Of Mary Beth Mulcahy
Sent: Thursday, November 01, 2012 10:00 AM
To: DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU
Subject: [DCHAS-L] identify demo?

Does anyone know what the demo in this experiment was suppose to be? I'm guessing ethanol environment that was suppose to be sparked and then fire shooting out of the openings in the pumpkin.

http://www.cnn.com/video/?hpt=hp_c3#/video/bestoftv/2012/10/31/bts-exploding-pumpkin-goes-awry.weht