Why dye eggs this Easter when you could make them detonate instead? An egg and some hydrogen gas make for a fun (but dangerous) physics demonstration. Check out a few explosions — and a few words of explanation.
A fun demonstration of pyrotechnics, and chemistry — and a little physics — begins with a hollowed out egg. The hollowing of the egg is, by far, the worst part of all of it, as those who have been subjected to Easter celebrations will know. First you have to put holes carefully in both ends of the egg, stab the yolk mercilessly, and blow the mess out of the thing without cracking the shell. Once you've got that done, you want to do something way more fun than just dying the egg yellow. You can't have more fun, because this kind of fun starts with hydrochloric acid and ends with an explosion, but you can at least watch other people under proper supervision having it, and know the science behind it all.
Let's begin with the acid. Hydrochloric acid is one hydrogen atom and one chlorine atom. It's found in gastric acid and is a strong acid used for industrial cleaning. When exposed to metals like zinc (or aluminum) the chlorine jumps ship and grabs on to the metal, leaving the hydrogen gas to bubble away into the atmosphere. A funnel placed over the container that the reaction is happening in can channel the hydrogen into the lower hole of the egg, while the upper hole of the egg is covered. When the egg is full, it's taken far away from the hydrogen and placed on a stand. The upper hole is uncovered and the egg is lit above the upper hole like a gas lamp.
It burns like a very ineffective gas lamp for a while, showing little flame, while the hydrogen leaks out the top. The egg, for a while, remains unscathed. The column of hydrogen leaking out the top is exposed to oxygen, which is necessary for oxidization, or burning. The inside of the egg is full of the stuff that blew up the Hindenburg, but the shell remains intact. If the egg really is full of hydrogen, any hydrogen gas inside won't have any oxygen nearby, and so it won't burn. As the hydrogen leaks out the top, though, oxygen rushes in through the bottom hole to fill up the vacuum left by the departing gas. At some point, there's enough oxygen in the egg to start the hydrogen burning, at which point the entire egg is blown apart. And yes, it looks cool, especially in slow motion. Oh, the poultry!