Instructions for the Exploding Eggs Demonstration and Experiment:
How to remove the inside of an egg
Needle or Pin
Start by making a small hole at one end of the egg with a needle or pin. Then make another hole on the opposite end. Unfold a paperclip and insert one end into one of the pinholes and scramble the egg yolk and whites; this will also cause the pinhole to become larger. Next, place your mouth over the smaller of the two holes and blow as hard as you can. Once pressure builds behind the egg, it will start to ooze out of the hole at the other end. Continue blowing until all of the egg has flowed out of the shell. You now have a hollow egg shell!
How to make Hydrogen gas from Hydrochloric Acid and Zinc
3 Molar Hydrochloric Acid (3M HCl)
The following link is for 12 Molar Hydrochloric Acid (also called Muriatic Acid). This acid is very dangerous because of the high concentration. To make 100ml of 3M hydrochloric acid from 12 molar hydrochloric acid: add 25ml acid to the flask and slowly add 75ml of water. This will generate heat and acid vapors so be extremely careful and use safety gloves, apron and goggles.
You may use a lower molarity [concentration] of acid but it will not produce hydrogen gas as quickly)
Erlenmeyer Flask (250ml)
Rubber stopper (#6, 1-hole)
Disposable Pipette (3 mL)
Cut the pointed end of the pipette off at about 2 inches and push the pointed end into the hole in the stopper so that the smallest part will be pointed out of the flask.
Pour about 100ml of 3M Hydrochloric Acid into the flask. Add several pieces of zinc turnings (this does not need to be an exact amount as gas will be generated right away. If bubbling slows, add more zinc and/or HCl)
Place the stopper into the flask. You should see gas coming out of the flask, into the pipette tip and floating up into the air. This is Hydrogen Gas and is highly combustible. Do not have open flame or spark next to this gas.
How to make an exploding egg
Slide the egg down onto the pipette tip. The egg should fill with gas and you will see the gas exiting out the other hole at the top. The egg is now filled with gas. At this point it will not likely explode as there is not enough oxygen left inside the egg to combust.
Hold your finger over the top hole (so they hydrogen gas will not escape) and place the egg in the same position on the mouth of a soda bottle (see video above).
Light a lighter. Remove your finger from the top hole of the egg and light it immediately.
A small flame will be burning at the top of the egg. Eventually the entire egg will explode with a loud bang and egg shell will fly in all directions!
The science: How does the exploding egg experiment work?
First, hydrogen gas is produced in the reaction between hydrochloric acid and zinc metal. The hydrogen gas is lighter than the air around it so it rises up into the egg during this experiment. Zinc chloride and water remain in the flask during and after the reaction.
Hydrochloric Acid + Zinc --> Zinc Chloride + Hydrogen gas
2HCl + Zn --> ZnCl2 + H2
Second, once the hydrogen gas has been lit on fire, the hydrogen reacts with oxygen in the air to form water. This reaction is exothermic and releases a significant amount of energy.
Hydrogen gas + Oxygen gas --> Water
2H2 + O2 --> 2H2O
Why doesn't the egg blow up right away?
As seen in the reaction equations above, hydrogen gas must have oxygen gas to combust (burn/explode). Inside the egg there is very little oxygen because it all gets pushed out by the rushing hydrogen coming from the flask. The hydrogen is very light so it will escape out the top and will mix with oxygen present in the air around it - this is why there is a flame at the top of the egg. As the hydrogen floats out the top, air is pulled into the hole in the bottom of the egg which contains oxygen. When a sufficient amount of hydrogen has escaped and enough oxygen has been pulled into the bottom, the ratio of hydrogen and oxygen is exact enough for the flame to move inside the egg. Due to the large amounts of hydrogen and oxygen inside the egg, it all combusts at the same time and pushes outward on the sides of the egg, causing it to explode!
Keep on Learning!
Craig Beals shows the crew at Montana This Morning on KTVQ (CBS) how to blow up eggs with hydrogen gas.