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Eggsplosions!
Eggsplosions!
This is a student favorite! It is one of my favorites also! The Calcium Hydride can be hard to come by but we are just generating hydrogen gas into the egg. I learned this demo from the late GREAT Robert Turkenton! Inventor of the Haz-Cat system! I took my Hazmat Tech with Mr. Turkenton! He used zinc and HCL at the time and that works, can be a bit slower though. The Calcium Hydride we use is from an old weather balloon generator and works great!
Concepts:
Flammable range (Lower Explosive Limit and Upper Explosive Limit), water reactive chemicals that produce flammable gases and caustic runoff.
Safety:
Safety glasses MUST be worn at all times by demonstrator and the audience
Safety shield is recommended to be placed in front of the audience and the demonstrator if safety glasses are not available.
Nitrile gloves as this demonstration can produce caustic products that are exothermic (VERY HOT).
Equipment:
Calcium Hydride (Millipore Sigma)
Sicssors
Matches
Eggs, XXL
Wooden skewer
Small knife
Bowl
Water & squeeze bottle
Preparation:
Grab an egg and place over a bowl.
Use the small kife to make a BB size hole at each end (Do not twist the knife it will crack the egg). You have to tap the knife to break the egg to make the small hole. You are basically making a confetti egg. Repeat on the other side.
Use the wooden skewer to push through one side of the egg through the other to break the yolk.
Blow out the contents into the bowl. This can be difficult (Caution raw eggs can contain Salmonella).
Once all the eggs are blown out let them dry for 24-48 hrs. Ensure there is good gas flow from one end to the to the other prior to use. You DO NOT want the hole too big, BB size is good!
Sometimes you may have to use a propane torch to dry out the eggs carefully!
Now, cut a pipette bulb in half and cut a slit in the side to allow easy application over a test tube.
Ensure the pipette will fit over the test tube with a snug seal and dry fit the egg on top of the pipette. You will have to hold this up to prevent it from tipping over. Optionally you could just set the egg on the test tube. But I learned it this way and it works so I do it this way.
Put about 1/4" of the Calcium Hydride into the test tube.
Place test tube into the test tube rack
Demonstration Instructions Lets do it! This will go fast you may need an assistant.
Have your assistant hold the egg and pipette.
Instructor will pour water from a squeeze bottle into the test tube until the material starts to bubble fiercely. Caution if you put too much water it may spit out of the test tube, the liquid can be caustic.
This will get VERY HOT do not hold in your hand
Quickly place the pipette on top of the test tube with the pointy end into the egg. Hold the pipette if necessary as the plastic will get hot and start to bend.
Keep it on top of the test tube for about 15 seconds, you want to see the gas pumping out of the top of the egg. This will saturate the egg with hydrogen gas (Flammable range 4-75%). You want to get it beyond the UEL.
Use a match and light the gas at the top of the egg. If lit too early the egg will pop as its in the flammable range. If above the UEL it will only light at the top of the egg. This is what we want.
SLOWLY pull the egg off the pipette and keep in a vertical position so the holes are north and south.
Extend your arm fully and wait, wait, wait. The anticipation is the fun part.
Observations:
If the egg pops immediately its within the flammable range. If not the flame will continue to burn at the top. The egg will explode when it reaches the flammable range as air fills the area where the hydrogen has left (Burned off) getting back to the flammable range inside the egg and igniting!
Video https://www.youtube.com/watch?v=Q2YcRFRf9ys https://www.youtube.com/watch?v=8JrOwZ42B0M
Learning Outcomes:
It is a FUN demo!
You can talk about flammable ranges (LEL-UEL) and chemical ractions with water reactive materials.
This demo creates a good amount of Hydrogen gas.
Extremely exothermic, talk about Thermal Imaging Cameras for reactions.
Also the products will be a caustic runoff as it makes Calcium Hydroxide.
Instrumentation for Hydrogen gas and cross sensitive sensors like Carbon Monoxide that will also have elevated readings on a 4-gas.
Chemical Disposal:
Collect ALL test tubes used for this demo and let them cool down. They will all need to quenched with water to ensure they are no longer reactive and then the ph adjusted to neutral with citric acid. Then dispose according to local regulations.
Additional Information:
Make a Hot Potato game! Circle up 5 students. When the egg is lit hand to one student who passes it to another.
Keep the egg vertical as it will help keep it lit
Sooner than later it will pop one of the contestants!
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