Sodium polyacrylate (a polymer found in clean disposable diapers or hydrogels )
Now Follow These Steps:
First: Collect sodium polyacrylate from inside a clean disposable diaper or hydrogels
Third: Add water.
Next: See what happens when you add more water. Add less water and a little salt and observe results.
Finally: Do you want your snow to feel and look more real? Refrigerate or freeze it. The gel will not melt. If it dries out, you can rehydrate it by adding more water.
Here’s What’s Happening!
When water is added to the sodium polyacrylate it is drawn to the center of the molecule by osmosis. Osmosis is the movement of water across a semi-permeable membrance from areas of low solute concentration to areas of high solute concentration. The ability of the polymer (sodium polyacrylate) to absorb excessive amounts of water is due to osmotic pressure (the minimum pressure which needs to be applied to a solution to prevent the inward flow of water across a semipermeable membrane). The sodium polyacrylate absorbs water until there is an equal concentration of water inside and outside.
What about the salt? Salt causes water to leak out of the sodium polyacrylate because it disrupts the attraction between water and the polymer chain. When salt is added, it breaks up into negative and positive ions, which are also attracted to the water molecules.