Sunday, March 14, 2010

Science Sunday: Epic Fail Ice Cream


 

So, we checked Howtoons out from the library about a month ago and ever since I’ve been wanting to make one of the experiments in there…….  Well, I finally got it all together, everyone was healthy and we had the time.  And that’s where it went downhill.  Oh, and my excuse of how it’s related to what we’re studying?  Wisconsin has lots of cows that produce a lot of milk, and milk is used to make ice cream.  Nice reasoning huh?
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I made these slightly bigger so you can see what the book looks like, and see the recipe I used.
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Bag 1: 1 C heavy cream, 1/2 C whole milk, 1/3 C sugar, 3/4 t vanilla
And those sneaky leprechauns came and turned the milk green.  Pesky guys.
Bag 2: 2.5 pounds of ice, 1.5 pounds of salt
As you can see I sealed the top of the bag with tape to make sure it didn’t burst open in the mixing.
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The kids quite happily helped pour the salt into the bag, and touched it and declared it was too cold.

Next, I put the first bag inside of the ice bag, which at that time was a 2 gallon bag.  So, when that got a hole within thirty seconds I decided it was because the bag was too big and more prone to tearing, so I switched to a gallon size bag, that was pretty much too small.  I don’t know what I was thinking.  Really, I don’t.

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Now, you’re supposed to toss it back and forth for 20 minutes.  As you can see it’s too heavy for the kids to do this.  Also, it’s cold.  They each patiently threw it once, and then said, “here Mommy.”  After everyone had their token toss I got the bag back and started shaking it when I noticed this:
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Do you see that forming on the bottom of the bag?  That’s a green drop of liquid.  That means not only did my ice bag burst, but my ice cream bag did as well.  At this point, the kids had lost interest, and it just wasn’t going to work.  So we went inside and ate Blue Bell ice cream.  And everyone was happy.  Actually I think I might sneak over and nab a few more cherries.

Oh, and I posted about this epic fail on facebook, and had a friend kindly give me another recipe that she says has worked for her several times.  When I try it next, I’m going to use this one:
"ZIPLOC ICE CREAM
1 tablespoon artificial
sweetener
1/2 teaspoon Vanilla Extract
1/2 cup Heavy Cream
6 tablespoons Table Salt
3 cups Ice
1 Sandwich Sized Ziploc
Bag
1 Gallon Sized Ziploc Bag
In the sandwich sized ziploc, combine the sugar substitute, vanilla extract and heavy cream. Seal the bag and shake lightly to mix ingredients.
In the gallon sized ziploc bag, add 3 cups of ice (or fill half the bag with ice)and add 6 tablespoons of table salt.
Place the seal sandwich sized bag into the gallon bag and seal the gallon bag. Shake the entire contents for at least 4 minutes (shake longer for harder ice cream).
Once desired hardness has been achieved, remove smaller baggies and rinse thoroughly with cold water (if you miss this step, you may wind up with salty ice cream!)
Recipe makes about a 1/2 cup of ice cream.
And here’s a scientific explanation of what happened from Teachnet (in case you can’t read the explanation in the picture from Howtoons):
What does the salt do? Just like we use salt on icy roads in the winter, salt mixed with ice in this case also causes the ice to melt. When salt comes into contact with ice, the freezing point of the ice is lowered. Water will normally freeze at 32 degrees F. A 10% salt solution freezes at 20 degrees F, and a 20% solution freezes at 2 degrees F. By lowering the temperature at which ice is frozen, we are able to create an environment in which the milk mixture can freeze at a temperature below 32 degrees F into ice cream.

So, anyone else have experiments that go wrong?  Obviously mine did, and I’m sad, but this lets us try again another time.
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