Summer Fun 2014 - Root Beer Floats - Experimenting With Nucleation

We had both diet, and regular root beer left over from a buoyancy/density test, for a sink or float experiment, to meet the final requirement on our library's science themed summer reading list...

...and Sunday just happened to be National Ice Cream Day.  It only seemed fitting to set up a summer, Sunday science, snactivity with root beer floats for everyone - including a few neighborhood friends who came running, when I called my own inside. 

First we talked about nucleation - the process of the carbon dioxide bubbles getting stuck in the craggy, oxygen bubble covered surface of the ice cream, where they sit pulling in more, and more bubbles, becoming larger and larger, creating a frothy, delicious, fat coated foam.  Then, I turned the children loose to experiment.

We made some floats by:

• dropping ice cream into the root beer,
• pouring root beer over small scoops of ice cream,
• pouring root beer onto ice cream, that had been pressed, and smoothed as much as possible into the bottom of the cup
•  and pouring root beer onto melted ice cream - which made a wonderful root beer fizz.

We used vanilla ice cream and:

• warm regular root beer,
• cold regular root beer,
• warm and cold diet root beer,
• and cold Coke Zero...

...observing the levels and quality of foam, and being delighted to find ice crystals forming in the root beer left to sit on top of the ice cream.  Some of our soda sat for a while before we got around to adding ice cream, and just as you might imagine, the foam was nearly as flat as the soda.

Then, just to be sure we were observing a physical change and not a chemical one brought on by combining ice cream and soda, we added some root beer to plain milk.

That brought our experiments to an end, as we switched over to a discussion of Laverne and Shirley, and Laverne's love of milk and Pepsi, and how I always wondered what that would taste like.  

If it's anything like root beer and milk, I wouldn't recommend it.



Resources we found handy:

How an Ice cream Soda or Float Works from About.com,
Kitchen Chemistry from Sciencecenter.org,
Fizzics from The Fizz,
and Why is There So Much Foam in a Root Beer Float?  from Wonderopolis.

Root Beer Float-Sicles

Did you know you could freeze a root beer float?

I didn't, but that's never stopped me from trying anything before. These frozen floats not only taste wonderful, they are super easy to make. Just scoop tablespoonfuls of ice cream into your popsicle molds, or Dixie cups, not packing it too full, so there are some empty spaces left in the molds.

Then, pour in the root beer, until the mold is full. Wait a minute or so, for some of the fizz to die down, and pour in a little more.

Add your sticks, and freeze for several hours. These are great treats to make, when you want root beer floats, but your running low on ice cream. And, they got a total thumbs up from my children.

It's great to be a homeschooler.

Summer Fun 2014 - Sink or Float? Sugared Ice-Cubes

I mentioned the other day that we had done a quick "sink or float" soda pop density experiment, to fulfill the final challenge for our library's summer reading program.  It was a simple - toss cans of diet, and sugared soda into a sink filled with water...

...to see which ones will sink, and which will float type of experiment.  Naturally, the diet soda floats, while the sugared soda sinks.

Actually, my children were more interested in the way the refracting light made the cans appear to shrink into mini-cans, in the water.  Since, it went along so nicely with the color video we had watched to go with our Kandinsky cookies, I let them play for a while...

...before bringing their attention back to the ingredient list on the sides of the cans.  All the cans of soda weighed the same, but they were not all the same when it came to their ingredients.  The sugar in the regular pop increases the density of the liquid, causing those cans to sink.  We also discovered not all diet soda is created equal.  The diet root beer did not have any sugar, but it had an amazing amount of salt, and not surprisingly it didn't float quite as well as the diet Coke (or at least it didn't appear to at the time).

The idea that the density of the liquid inside of a closed can of soda can have more to do with whether the can will sink, or float, than the weight of the can, can be hard to wrap your mind around.  I wanted to be sure the younger children were really getting what was happening, so I prepared a second experiment...

...by filling, and freezing an ice-cube tray, filled half with plain water, and half with sugar dissolved in boiling water to as close to the saturation point as I could take it.

Once the ice was frozen, I plopped one of the plain cubes into a glass of water, and asked the girls if they knew why it floated.  They more or less remembered, that water becomes less dense as it freezes (you can find a more complete explanation, here), which I thought was good enough for an 8 and 9 year old.

I plopped in a sugared ice-cube, and asked the surprised girls why they though it sank, and watched the "light bulb" go on, as I asked them if they remembered why the can of regular soda didn't float, when they diet soda did.

"Sugar!" they yelled, and then, of course, "Can we taste it?"

It's great to be a homeschooler.