We have created a set of instructions so visitors can conduct this experiment without the guidance of a Museum volunteer. I am happy to share if you would like to see what we have.

nnolan@mos.org [20]

We use a mortar and pestle and let the visitors grind the tablet. They break one tablet into 2 pieces (so it doesn't wedge partway down the cylinder), and then we transfer(can be dusty) the ground second tablet into the 2nd cylinder using a funnel and paint brush.
Before we (or the visitors) add the colored water we ask 'how many pieces in the first cylinder (2) and how many in the second (million, billion, countless, etc!). It makes for a very quick and dramatic reaction and great discussion.

They love to do it again and sometimes we also do an extension with them where we've added a drop of detergent to a different color water. When this reacts the gasses are captured and there is a great head of bubbles that helps visualize it. We use different graduated cylinders or Erlynmeyers for these experiments.
Surface Area is a great/dramatic activity and demo!

The Science Museum of Minnesota has a shorter version of this program. The Science Museum's 'hack'is approximately 15 minutes in duration and is meant for large audiences.

Our success with this program has been largely due to adding NISE content into a demonstration about basic chemistry.

Please contact Stephanie Long for more information.

Stephanie Long
slong@smm.org [27]
651-221-2587

I have used a simple method for kids to break an antacid tablet into tiny pieces without making an extraordinary mess and without using a mallet.
You will need a sheet of 8.5 by 11 inch paper. The paper can be used and ready for recycling.
You will also need a marker. Used up markers work well as The participants will not be writing with the marker. Braod tip, children's non-toxic markers are fine. The marker cannot have a clip on it. 3/4 inch dowels cut into 5 inch lengths will also work.
Fold the sheet of paper in half (either vcertically or horizontially). Place one antacid tablet in the middle on the center of the crease. Press down and roll marker (or dowel) back and forth over the paper with the antacid inside. Press down hard and continue until the antacid tablet is a fine powder. Tap the powder gently into the center of the crease. Lift the paper and gently pour the powder into the cylinder.

I definitely recommend getting your small pieces of alka-seltzer into as small of pieces as possible - grind or pound that stuff into a powder!

One idea for extra visitor involvement - have them do the grinding. You could use a mortar and pestle or simply have them tap on the tablet with a hammer repeatedly.