Homeschooling my 5 yr old, we have been doing simple experiments with tap water. One such experiment involved the evaporation of water from an open-mouthed jar at room temp. For curiosity sake, a second jar was placed beside it with a solution of salt water. (a third jar of tap water with a lid was used as a control.)
While the tap water is evaporating as expected, the salt water is evaporating equally well. However, crystals of salt (presumably) have formed on the water’s surface in the shape of tiny snowflakes. The tap water has nothing floating on its surface, so it is not dust, for example. If this is salt, I thought the lattice of a salt crystal (NaCl) could only form in a cubical geometry.
Can someone explain what is happening here? Does NaCl have an alternate lattice structure…such as that typical of the transitional elements?
Perhaps you’ve considered that salt was not the only thing dissolved in your water samples. The other minerals in the tap water could have affected the crystal shape.
Yes, that thought crossed my mind. My first thought was that those same impurities are present in the sample of tap water, too. But, perhaps the NaCl crystals are becoming doped as they settle out?
The next step is to repeat with distilled water, and see what forms…
I think that it would have something to do with the salt forming in cubes on a smaller level than the snowflake pattern you see. The salt is forming cubes, just at a smaller level. Like a snowflake made of cubes.
Take what I said with a grain of salt, though… I’m not quite sure it explains it. I think so, though.
Just how much salt did you put in the water. Sounds as if there was enough to make a saturated solution. This would cause supersaturation or the deposit of salt crystals on the sides of the glass jar. Never have seen floating crystal such as you describe.
You may have just made an artificial version of fleur de sel, which is the crust that forms on the top of seawater when it’s evaporated, and is sold for exorbitant prices. Here’s a rough translation of the link; there’s a bit of technical vocabulary that I can’t translate: