From: Eric Plett (EPlett@serrahs.com)
Date: Tue Feb 11 2003 - 09:00:01 PST
Message-ID: <400AF0ECEABFFD45868C4BD0A0A43D2F069853@SERRA-EXCHANGE> From: Eric Plett <EPlett@serrahs.com> Subject: Safe explosions Date: Tue, 11 Feb 2003 09:00:01 -0800
Hi Tamra,
We do three explosions during the year: Sodium reaction (in a bucket outside
with the class 30 feet away), Dry ice bombs (in Gatorade bottles outside
with the class 50 feet away! They can shoot up like a rocket.), and Gas in
a Can (natural gas in a paint can - in the classroom). The safest of the
three (I've actually held the can in my hand while it explodes) is to
prepare a 1 gallon paint can by cutting a 1/4 inch diameter hole in the lid
AND in the lower side of the can. Fill it completely with natural gas.
Light the top and let it go. It is a very controlled explosion and usually
does not even bother neighboring classes. Be extra careful your first
couple of times until you start to figure out the extent of the explosion.
Perhaps practice after school first. Have the students write observations
on the progression of the flame and try to figure out why it finally blows
up. The flame will slowly burn so that it is barely visible and then the
lid will blow off sometimes hitting the ceiling. The more firmly the lid is
put on, the more forcefully it will blow off. The can will be warm
afterward. The class should be at least 4-8 feet away. Be careful not to
approach it thinking that the flame has gone out - that's when it is going
to blow. Also be careful to COMPLETELY fill the can with gas from the top
(methane is lighter than air) until you smell gas coming out of the side
hole or it may blow as soon as you light it!
Eric Plett
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