Soda Can Science

My science club has hit a bit of a plateau. I only get 3 to 5 kids, and their ages are so varied that it's hard to find something that interests all of them. I read somewhere in my travels that diet soda floats, while regular soda sinks (Really!!), so I designed this density experiment to celebrate the awesomeness of this fact. 

This week, I only had three kids for Science Club  - but they were all of similar age, and they all had a fantastic time. Plus, it was easy!

What You Need

• A large clear plastic tub mostly filled with water
• 6 cans of soda - a mix of regular and diet (please note: this doesn't work with mini cans)
• Canister of salt
• 2 plastic cups
• Kitchen scale
• Something to stir with (we used a ruler)
• About 20 sugar packets
• About 20 artificial sugar packets
• Orange (nice but not required)
• Aluminum foil (optional)
• Willing kids to participate (hereafter referred to as your scientists)

What To Do

The Optional Part
Place the tub of water on a table so everyone can see. Shape your aluminum foil into a little boat. "Will this float, or sink?" Your scientists will all agree that it floats. Demonstrate.

Crumple the foil into a ball. "Will it float now, or sink?" (Please note: you need to crumple it REALLY WELL, or it will continue to float, and you will look silly.) The scientists usually agree that it will sink - if you did it right, it will. So, what changed? The density changed, which is a measure of how much something weighs compared to how much room it takes up. 

"Will the orange sink or float?" You may get differing answers on this one but the orange should, in fact, float. Neat. What if we peeled it? Your scientists will probably agree that it will still float, but they will be surprised to see it sink! Why? Because the orange peel has so much air in it, it acts as a flotation device, like if you wore a life jacket when you went swimming. So what does it mean if it doesn't have as much air in it? The orange without the peel is more dense. (You see where I'm going with this.)

The Rest Of It
SO! Will a can of soda float, or sink? Drop the cans in one at a time, starting with a regular (non-diet) soda. It will sink. ("Duh," I was told.) Then, try a diet can. It... floats? WHAAAAAAT? Continue with all of your cans. 

What's the difference between the cans that sink and the cans that float? The ones that float are DIET sodas. So what's the difference between a regular soda and a diet soda? Fish out all the cans and take a look. (You can put your tub of water aside now, if you have room.)

The sodas all have the same amount of liquid in them - that's the volume. Put them on the scale one by one and notice that the diet sodas weigh less than regular sodas. This means that the regular sodas are more dense than the diet ones.

This is 16 packets of sugar.

But why? Well, take a look at the sugar content of the sodas. The regular soda cans that I had each had 49 grams of sugar (!) while the diet ones have sugar substitutes in them.

Put an empty plastic cup on your scale and zero out the weight. Ask the scientists to add enough sugar to make 49 grams, and count how many packets of sugar that takes. (Our count was 16 packets. SIXTEEN PACKETS, in one can of soda!)

Put a new cup on the scale and zero it out. Now, take 16 packets of artificial sugar and see how much that weighs (about 16 grams). Allow the kids to feel the difference in the weight of the cups, and also the weight of unopened packets. Wow, so that's why it's such a difference in weight, and therefore in density!

If you have moved your water tub, it's time to bring it back. Ask if anyone has any ideas on how to make all the soda cans float. (Mine didn't, aside from pouring out the cans.) "Well, we can't change the density of the cans, but we can change the density of the water." Bring out a container of salt and allow the scientists to pour it (all of it!) in, and stir (we used a ruler for this) until it was as dissolved as possible. 

We put the cans back in and noticed that the diet ones bobbed at the surface even more than before. The cans on the bottom sank more slowly than before, but when one of our scientists started stirring the "soda soup," we noticed that the cans moved when the water moved - it was hard to see, but they were, in fact, floating. Magic? No! Science!

Kat's Note: because of the sugar content of ginger ale, which is less than most cola, orange soda, and grape soda, ginger ale will float, but not as high in the water as diet soda. Maybe skip the ginger ale.

Lab Report

I made this lab report with Canva. I have it in PDF form; just shoot me an email if that works better for you. Otherwise, right click and save these images and paste into a Word document to print.