We've been working our way through a fun book about the Periodic Table called "
Fizz, Bubble & Flash" by Anita Brandolini which explores elements and atoms in a hands on way. The first section is on Hydrogen and the Alkali Metals family which is what leads to ice cream. Sodium and its relatives in the Alkali Metal families are highly reactive to water and/or air. We checked out some fun and interesting
videos showing what happens when bare alkali metals are exposed to air and water.
The first thing we did was to mix up a simple ice cream mix. 1/2 heavy cream, 1/2 milk, a little sugar and a little vanilla - seal in a bag. This bag is placed in a larger plastic bag with ice. Shake for about 10 to 15 minutes and observe that the ice cream mix is colder but not ice cream.
Next add salt to the ice and start shaking again. Shake for about 10 to 15 minutes. It is definitely colder - using an oven mitt or a kitchen towel helped. Also the bag had a lot more condensation on it. In short order we had ice cream!
Yum!
A close up on the ice cream in the baggie.
To further demonstrate the effect of salt on water we had also frozen plain water and salt water. It took a lot longer to freeze the salt water. Salt (sodium chloride) lowers the freezing point of water. In fact it didn't quite freeze all the way. Also the salted water was blue. As I was browsing around the the book I noticed that it said that Iodine usually evaporated. My guess is that the iodine was trapped in the frozen salted water. When we thawed the water out the blue color remained but was gone the next day.
We've been working our way through a fun book about the Periodic Table called "Fizz, Bubble & Flash" by Anita Brandolini which explores elements and atoms in a hands on way. The first section is on Hydrogen and the Alkali Metals family which is what leads to ice cream. Sodium and its relatives in the Alkali Metal families are highly reactive to water and/or air. We checked out some fun and interesting videos showing what happens when bare alkali metals are exposed to air and water. 
The first thing we did was to mix up a simple ice cream mix. 1/2 heavy cream, 1/2 milk, a little sugar and a little vanilla - seal in a bag. This bag is placed in a larger plastic bag with ice. Shake for about 10 to 15 minutes and observe that the ice cream mix is colder but not ice cream.
Next add salt to the ice and start shaking again. Shake for about 10 to 15 minutes. It is definitely colder - using an oven mitt or a kitchen towel helped. Also the bag had a lot more condensation on it. In short order we had ice cream!
Yum!
A close up on the ice cream in the baggie.
To further demonstrate the effect of salt on water we had also frozen plain water and salt water. It took a lot longer to freeze the salt water. Salt (sodium chloride) lowers the freezing point of water. In fact it didn't quite freeze all the way. Also the salted water was blue. As I was browsing around the the book I noticed that it said that Iodine usually evaporated. My guess is that the iodine was trapped in the frozen salted water. When we thawed the water out the blue color remained but was gone the next day.
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