Get Bismuth Metal from Pepto-Bismol Antacid Tablets

Pepto-Bismol is a common antacid medicine that contains bismuth subsalicylate or pink bismuth, which has the empirical chemical formula (Bi{C₆H₄(OH)CO₂}₃). The chemical is used as an antacid, anti-inflammatory, and bactericide, but in this project, it is used for science! Here's how to extract the bismuth metal from the product. Once you have it, one project you can try is growing your own bismuth crystals.

Bismuth Extraction Materials

There are a couple of different methods for isolating the bismuth metal. One way is to burn Pepto-Bismol into a metal oxide slag using a blow torch and then separate the metal from the oxygen. However, there's an easier method that only requires household chemicals.

Here are the materials to extract the bismuth, without fire.

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Grow Metal Crystals

By Anne Marie Helmenstine, Ph.D.

• Pepto-Bismol Tablets: You need a lot. Each pill contains 262 mg bismuth subsalicylate, but only about an eighth of the mass is bismuth.
• Muriatic Acid - You can find this in a hardware store. Of course, if you have access to a chemistry lab, you can simply use hydrochloric acid.
• Aluminum Foil
• Coffee Filter or Filter Paper
• Mortar and Pestle - If you don't have one, find a baggie and a rolling pin or hammer.

Get the Bismuth Metal

1. The first step is to crush and grind up the pills to form a powder. This increases the surface area so the next step, a chemical reaction, can proceed more efficiently. Take 150-200 pills and work in batches to grind them up. Aside from a mortar and pestle or bag with rolling pin or hammer, you could opt for a spice mill or coffee grinder. Your choice.
2. Prepare a solution of dilute muriatic acid. Mix one part acid to six parts water. Add the acid to the water to prevent splashing. Note: muriatic acid is the strong acid HCl. It produces irritating fumes and can give you a chemical burn. It's a good plan to wear gloves and protective eyewear when you use it. Use a glass or plastic container, as the acid can attack metals (which is the point, after all.)
3. Dissolve the ground-up tablets in the acid solution. You can stir it with a glass rod, plastic coffee stirrer, or wooden spoon.
4. Remove the solids by filtering the solution through a coffee filter or filter paper. The pink liquid is what you want to save since it contains bismuth ions.
5. Drop aluminum foil into the pink solution. A black solid will form, which is the bismuth. Allow time for the precipitate to sink to the bottom of the container.
6. Filter the liquid through a cloth or paper towel to get the bismuth metal.
7. The final step is to melt the metal. Bismuth has a low melting point, so you can melt it using a torch or in a higher-melting-point pan on a gas grill or even your stove. As the metal melts, you'll see impurities pool apart. You can use a toothpick to remove them,
8. Let your metal cool and admire your work. See the beautiful iridescent oxidation layer? You might even see crystals. Good job!

Safety and Cleanup

• This project requires adult supervision. Keep kids and pets away from the acid and heat.
• When you're done, dilute the chemicals with large volumes of water before disposing of them. If you want to make absolutely sure the acid is safe, you can add a bit of baking soda to the dilute acid to neutralize it.

Pepto-Bismol Fun Facts

Interesting adverse effects from ingesting Pepto-Bismol include black tongue and black stools. This occurs when sulfur in saliva and the intestines combines with the medicine to form the insoluble black salt, bismuth sulfide. Although dramatic-looking, the effect is temporary.

Sources

• Gray, Theodore. "Gray Matter: Extracting Bismuth from Pepto-Bismol Tablets." Popular Science. August 29, 2012.
• Wesołowski, M. (1982). "Thermal decomposition of pharmaceutical preparations containing inorganic components." Microchimica Acta (Vienna) 77(5–6): 451–464.