What’s an Acid Bomb?

Can I get one at Wal-Mart?

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Two teenage boys in Maine set off a pair of acid bombs at a Wal-Mart on Saturday, one of the biggest shopping days of the year. Several other adolescents have made and detonated similar devices in recent weeks. What’s an acid bomb?

A plastic bottle filled with an acid and a reacting base. Acid bombers make use of the same type of chemical reaction that causes vinegar and baking soda to bubble up when you mix them together. The bombers fill a bottle with hydrochloric acid or something else with a low pH, and add a strong base, like drain-clearing liquid. They might replace one of these ingredients with aluminum foil, which can react with either an acid or a base. * Then, they shake it up. If they’re using the right kind of base, the combination of the chemicals will produce a gas. (For vinegar and baking soda, it’s carbon dioxide.) The gas builds up pressure inside the sealed bottle until it explodes.

An acid bomb (which is also called a “bottle bomb” or a “MacGyver bomb”) doesn’t have a timer to set or a fuse to light, and you can’t predict exactly when it will explode. If your device works, its contents should begin to bubble after you shake it up, and the plastic bottle may swell before it bursts. The whole process generally takes a minute to begin, which gives the bomber a short time to make a getaway. (This video clip shows the delay before an acid bomb blows up.)

Once one of these bombs explodes, the chemicals can spray out and injure bystanders. Chemical burns and irritation of the eyes, skin, and respiratory system are the most common effects. (The range of the spray can vary widely, depending on the chemicals used and the volume of the bomb.)

The materials of an acid bomb are readily available, though not necessarily at Wal-Mart, which sells aluminum foil but not hydrochloric acid or ammonia. Both corrosives are regulated in the United States and can be a bit difficult to obtain. (A teenage boy from Texas who was arrested for making an acid bomb said he acquired his ammonia in Mexico.)

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Correction, Nov. 30, 2006: This article originally identified aluminum foil as a strong base. It displays the characteristics of both an acid and a base. (Return  to the corrected sentence.)