I started a Pinterest board of things to do with the kids in preparation for the December holidays ahead of us. My 7-year old saw the page open on my laptop and immediately wanted to ‘do something’. He watched the Naked Egg video that we found online and was inspired even further. Here’s the video:
So, a “naked egg” is an egg that has no shell but the egg stays intact! It’s all squidgy and it bounces! The egg remains intact due to the solidification of the membrane that you find under the shell – the white skin that you are familiar with. The albumen and yolk remain viscous.
An eggshell is made up of primarily calcium carbonate. If you soak this egg shell in vinegar (which is about 4% acetic acid), you start a chemical reaction that dissolves the calcium carbonate shell. The acetic acid reacts with the calcium carbonate in the egg shell and releases carbon dioxide gas that you see as bubbles on the shell.
All you need to make your own Naked Eggs are: raw eggs, vinegar and glass/transparent containers to put the eggs and vinegar into. Our eggs were ready after a day and a half of soaking – possibly earlier but I didn’t want to take chances knowing that the kids had high expectations from this project.
Start by simply dropping the eggs into your container of vinegar.
You can see bubbles appearing almost immediately as the chemical reaction occurs. This is the acetic acid in the vinegar reacting with the calcium in the egg shell. The bubbles are carbon dioxide gas from the reaction.
I read that a good sign of progress is a white frothy scummy layer on the top of the surface of the vinegar and was really relieved when our mix got really frothy. The pic below shows the froth forming after just 1 hour into the experiment.
After 24 hours carefully remove the egg from the vinegar using your hand and not a hard spoon or utensil. At this point you may be able to literally rub the shell off the egg with your fingers. It will rub off as a white powdery substance.
After 12 hours there was a lot more froth and it was also noticeably more brown than before. This is the result of the dissolving eggshell into the vinegar. The eggs were also considerably bigger than when we bought them from the store. (In fact, they reminded of what standard eggs looked like in the “good old days”). This is because some of the vinegar (and some of the water in the vinegar) has moved through the membranes to the inside of the egg. The membranes are semi-permeable and allow water to move through them (osmosis).
18 hours later our eggs were continuing to grow in size but the froth wasn’t forming exponentially. At this point you can transfer the eggs into a fresh container of vinegar. I didn’t – by this stage I was so over watching eggs grow and just wanted to get to the bouncy fun part. Also, the 7-year old had grown quite protective over the eggs and was now seen dragging and hiding the science project to keep it away from his 2-year old brother. This morning I nearly took a swig of vinegar because the container had been placed on my bedside table where my coffee cup usually goes…
The kids agreed to do the colouring activity first (you can see the food colour move through the membrane of the egg) in case the bouncing bit didn’t work out so well. Good idea kids! The highlight was of course getting them to bounce the eggs. When the eggs popped we saw that they were completely raw as they would be if you just cracked open the shell but the membranes were now inked with food colouring and were quite leathery in texture.
Here are some pics from our day with the eggs.
I have 2 short video clips; the first one is the beginning of chaos 🙂 and the 2nd video shows our successful bouncing egg!
We didn’t try the corn syrup experiment as 1. we don’t have the patience and 2. our eggs had already popped . Your eggs will shrivel up and look like… well, just take a look at the pic to the Right that I found on the web. If you get tired of the raisin egg look, you can reverse the process by putting the egg back in a cup of water. The water will once again move across the membrane and fill the egg with water again.