NANO AT HOME: An Experiment That You Can Try
PLEASE NOTE: The Center for Nano- and Molecular Science and Technology (CNM) at The University of Texas at Austin (UT-Austin) cannot guarantee the accuracy or the safety of these activities. Some of these activities might pose safety hazards for young children, and all activities should be performed under the supervision of a responsible parent, teacher or adult. The CNM and UT-Austin do not assume any responsibility for these activities or their results. If you have questions, corrections, or comments please do not hesitate to contact the CNM.
This demonstration is a twist on the classic homemade volcano, in which vinegar and baking soda chemically react in a model of a volcano to produce sodium acetate, water, and carbon dioxide gas. The carbon dioxide bubbles up out of the model to produce bubbling “lava” which oozes out of the “volcano”. The picture below shows the same reaction in a soda bottle (food coloring and dish soap have been added to make the lava flow more impressive).
But what about the volcanoes with more explosive eruptions? Here we adapt another classic demonstration involving film canisters and Alka-Seltzer tablets.
Materials that are needed:
eye protection like lab goggles
plastic film canister with lid (ask employees at film-developing places like Walgreens)
towels to mop up the mess
plastic sheet to place under the experiment to aid cleanup
Materials that are optional:
modeling clay or some other material to make a volcanic cone
red and yellow food coloring
milk jug cap
fiery looking (like orange) glitter
Wear your eye protection.
First lay down a sheet of plastic to make cleanup easier. Place a film canister into a clay volcano, setting the lid aside for now. Fill the milk cap with glitter. Fill the film canister halfway with water, with maybe a little dish soap and red and yellow food coloring for a “lava” effect. Break a tablet of Alka-Seltzer in half (any more that is wasted). Make sure everything is ready and the area is cleared out around the volcano.
Then, QUICKLY add the half-tablet of Alka-Seltzer to the film canister, cover the canister tightly with the lid, place the milk cap full of glitter on top of the lid, and take a step back (NEVER stand over the lid). The citric acid and baking soda in the tablet dissolve in the water and chemically react to produce sodium citrate, water, and carbon dioxide gas. The gas pressure builds up in the capped film canister until the lid pops off, scattering the glitter and sending reddish suds oozing down the side of the volcano.
OK, so where is the “nano”? Well, besides the fact that these models are much smaller than real volcanoes, we can use the Alka-Seltzer tablets to illustrate the effects that size has on processes. If the half-tablet that is added to the film canister is first broken into small pieces, it will dissolve much more quickly in water to react and produce carbon dioxide gas. The result is that, with all else equal, a popper volcano with the broken-up half-tablet will pop more quickly after loading than one with an intact half-tablet. This illustrates how processes can proceed more quickly at smaller scales. For example, many people are studying how making things really small (at the nanoscale) with lots of surface area can speed up chemical reactions.
Another note: We have also noticed that a film canister fits into the top of a milk jug with just a little widening (we also colored the jug piece with permanent markers). This seems to be very inexpensive way to make a waterproof volcano cone without having to use modeling clay.