Sunday, March 17, 2013

Four Eggxperiments

I've recently learned about Pinterest and set up a Desert Survivor Pinterest account that has lots of things from this blog and other blogs. One of the things I like about it is that I can get ideas for healthy recipes and kids' science experiments easily. I found one post that had 10 egg experiments and clicked through to the website. I also looked around at some other websites to get additional ideas. In the end, we decided to do four egg experiments (Desert Boy called them eggxperiments) yesterday. This is a long post. But it's fun!

Eggxperiment #1: Stand on eggs
Hypothesis: Standing on raw eggs will crush them and make a huge mess
(Desert Boy was even getting cleaning supplies ready before we began. He totally didn't think this would work.) Idea from this website.

Eggs are strong, but are they that strong? We decided to find out.
Desert Boy thought I was crazy when I told him to step on the eggs.

Step 1: Get raw eggs. I thought we had a lot, but it turned out we only had part of a carton. Oh well, my kids have little feet.

Step 2: Try to make sure all the eggs are about the same height.

Step 3: Have your test subject put a foot lightly on the eggs.
Step 4: Transfer weight to the eggs. See what happens!

The eggs didn't break.
Desert Girl wanted to give it a try too.
The eggs didn't break under her weight either. (Do you like her backpack? She likes to pretend she's in school.)

So if you have enough eggs, the eggshells are strong enough to support your weight (at least if you weigh 40 pounds or less). But what about just one egg? Is it strong enough to support 40 pounds? We decided to give it a try.
We were all a little nervous about this one.
But, as it turned out, the egg didn't break! We may have to try this again next year to see if a few extra pounds make a difference. For now, though, we had to reject our hypothesis. Standing on eggs did not break them and make a huge mess (for which I was quite grateful).

So why didn't the eggs break? Eggs are natural examples of arches, one of the strongest forms in nature and in modern architecture. The arch distributes the compressive forces, which means that the weight is spread out and not focused in one spot.

Eggxperiment #2: Break a raw egg with your hands
Hypothesis: With bare hands, it will be possible to squeeze an egg so hard that it breaks.
Kids like making messes, so these eggxperiments trying to make messes are extra fun. For this one, we wanted to break an egg with our hands.

Step 1: Put a raw egg into a Ziploc bag (or put cling wrap all around it). Make sure the egg doesn't have any cracks in it.

Step 2: Squeeze the egg as hard as you can.

Desert Boy is trying really, really hard to break it!

It's still not breaking!

Desert Girl wanted a try, too. She couldn't break it either.

So how about some teamwork?
Even with double the power, they still couldn't break the egg.

Is the Ziploc bag creating some magical field? Hmm, we can take it off and try breaking it over the sink.
Once again, we couldn't get the egg to break. So we'll reject this hypothesis too. With bare hands, we weren't able to squeeze an egg so hard that it would break.

Again, the arch shape of the eggshell is providing strength. A chicken eggshell is made of 95-97% calcium carbonate supported by a protein matrix. The older the hen laying the egg, the weaker the eggshell. But it's still stronger than you might think!

Eggxperiment #3: Make an egg float
Hypothesis: If we add enough salt to water, it will make an egg float.
One way to have a floating egg is to have an old egg. If an egg is older than 4 weeks old, it is more likely to float because the eggshell is somewhat porous and the water vapor and gases slowly leave the eggshell.

But how can you make a fresh egg float? It's all about density. Is it easier to float in fresh water or the ocean (or Great Salt Lake)? Desert Boy remembered that it was easier to float in the ocean, because it has salt in it. So we wanted to make the egg float by adding salt.

Step 1: Put a raw egg in a bowl of water. Watch it sink to the bottom.

Step 2: Start adding salt.
Step 3: Stir in salt. (I realized after we started that if I had used warm water, the salt would dissolve faster).

Step 4: Keep adding salt (we had to add about 6 Tablespoons).

Finally, the egg floats! We didn't have to reject this hypothesis. Our experiment turned out how we expected.

If I had to do this again, I would use a narrower, taller glass container and pour the salt in faster (maybe a quarter cup at the beginning to get things going), plus use warm water.

Eggxperiment #4: Squeeze a hard-boiled egg into a bottle without pushing it with our hands
Hypothesis: No way! We will not be able to fit an egg into a bottle with a mouth that is narrower than the egg

We saved the best eggxperiment for last. Could we get a hard-boiled egg into a bottle that had a neck narrower than the egg? Desert Boy doesn't think so.

Step 1: Get a bottle with a neck just slightly narrower than your hardboiled egg. (We used a plastic bottle, but all other instructions I've seen say a glass bottle).

Step 2: Put a little oil around the rim of the bottle.

Step 3: Light two matches and put into bottle.

Step 4: Put a peeled hard-boiled egg immediately on top of bottle.

We made a video of our first attempt:

It didn't work! I feel it's important to share that we don't always have success with our science experiments. Should you give up if it doesn't work? No way! We thought about what happened--the matches went out. Maybe we needed something that burned better. So we revised step 3.

New Step 3: Light a strip of paper on fire and place in bottle.

Here are our results:

Hurray, it worked! In fact, it was quite impressive how fast that hard boiled egg was sucked into the bottle. Some of the egg white even sheared off. (Did you see that in the video? If not, watch again, it's cool.)

So why does this happen? Air pressure is the short answer (and the one Desert Boy remembers). The longer version is that when you heat a gas, it expands. The air in the bottle is expanding with the lit paper and matches, and some of that escapes past the egg sitting on the top. Once the fire is out, the air cools. Because some of the air molecules had escaped the bottle, there are fewer to occupy the same space, creating a small vacuum. The outside air pressure is stronger, and it pushes that egg into the bottle.

I'm guessing with just the two matches we didn't have enough air molecules leave the bottle, thus the vacuum wasn't strong enough to pull the egg into the bottle. With the more flammable paper, more air was displaced. Did you notice that the egg didn't start moving till the flame was out? (I didn't at first, I had to watch it again!)

So we rejected our hypothesis. We really could get an egg into a bottle with a narrower neck.

Well, that was so much fun that we had to try a little twist on it, which I found in Naked Eggs and Flying Potatoes: Unforgettable Experiments That Make Science Fun (Steve Spangler Science). This time we put two birthday candles on the top of an egg, lit them, and put the bottle on top. We tried to suck the egg up into the bottle.

Alas, that didn't work. We tried three times. The egg went partially into the bottle, but not all the way. I'm not sure if it's because this hard-boiled egg was slightly rounder, or if it's because we live over a mile above sea level and the air molecules aren't as dense here, or if it's something else entirely. We'll be trying this again another day.

So what do you do with the hardboiled egg? Make a bunny! (See this pictorial to learn how.)
Now we have a connection between bunnies and eggs.

Have fun with your eggs! (Coming soon--how to dye your hard-boiled eggs with homemade, non-toxic dyes).

Have any other eggxperiments we should try?


jhami said...

Haha Very cool

Anonymous said...

The incredible, edible egg! We loved the blog on the eggxperiments. I want to try to squish an egg in my bare hand! Maybe tomorrow. Ru-ru thought that when the bottle is on top of the egg, gravity is pulling the egg away from the bottle. Anyway, very cool post with fun videos!! Nerd

Desert Survivor said...

Nerd, you should definitely try to squish an egg with your bare hand. It's a lot of fun to try!

Anita's Antiques said...

That is neat that you do experiments with your children

Alex Nguyen said...

hi! thanks for visiting my blog, and doing the standing on eggs experiment! :) My kids were also adamant that "the eggs would be smusted". You can check out my "science experiment" tag under categories if you're looking for more sciencey things to do with the kiddos. Thanks again for the link back! :) looks like you guys had a great time with your different eggsperiments!

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