Salt Is Fascinating

Who knew salt could be so fascinating? We are learning about the ocean in our Zoology course. A few weeks ago we read a chapter overviewing tides and currents, how they are made, what affects them, etc. One type of current is called thermohaline. This is a current that is affected by both temperature and salinity. Did you know that the freezing point of salt water is lower than the freezing point of regular water? We didn't! We decided to do a simple experiment of adding salt to some water and placing it in the freezer to see the difference. We did this one morning and really expected it to freeze at least by evening. We didn't add much water... about a half of a cup, heated it in the microwave to dissolve the salt, placed salt in it (we didn't measure). Then we waited, and waited, and waited.

It took about 4 days if not more to freeze this little bit of water with salt in it. If I had known it would take so long and been so fascinating we would have taken more notes. But, everyday it looked different. Sometimes the top had a small crust of frozen water on top. We'd look again and the top would be broken up and the pieces in the middle seemed to be cracking. It would look frozen and then frosty and finally all frosty and frozen. We noticed the small square crystals that formed on the sides and examined them under the microscope. The kids were delighted to see that the crystals formed in perfect squares with no mold... imagine that! We hope you will do this very simple experiment just to see the fascinating aspects of something so seemingly simple as God adding salt to the oceans waters. It affects everything.

Well, it was so fascinating in the freezer that I decided we'd take it out and watch it for a few days as it thawed. It only took it about an hour to thaw but we continued to watch it for several days. The whole process generated many thought provoking questions. Why did the salt accumulate on the sides of the glass so thickly? Why was there some salt on the bottom of the cup and even on the counter outside of the glass? Where does the salt come from? It all has to do with the water cycle. The water cycle in textbooks and even explaining it conceptually seems really quite boring. But, seeing it in action has illuminated the process in all of our minds. Seeing really is believing. Have fun!