How to grow and shrink gummy candies
How to resize gummy candies
Is it possible to change the size of a gummy candy? It sure is! Find out how in this cool video!
Perform this experiment only under adult supervision.
Reagents and equipment
- 2 glasses;
- gummy candies;
- saturated sodium chloride solution (4 tbsp per cup of boiling water).
Distribute a few gummy candies among two glasses. Fill one glass with water, and the other with a saturated sodium chloride solution (4 tablespoons per cup of boiling water). 10 hours later, you will see a significant difference between the contents of the glasses. The gummies in water have grown, and the candies in the salt solution have decreased in size!
Gummy candies contain gelatin, a polymer of natural origin that, due to its structure, can absorb and retain water. Water molecules are relatively small and can seep into the intermolecular spaces in the gelatin. Once in the gelatin, they remain there due to the formation of hydrogen bonds and so, gelatin swells in the water!
The reverse happens in a table salt solution: the water in the candies is pulled into the solution. The water molecules are attracted by the excess of ions in the salt solution, and abandon the gelatin to surround the ions in a “coat” of sorts. Water molecules are structured such that they have two poles: one positively charged, one negatively charged. Each water molecule orients itself so that the pole facing the ion it interacts with has the opposite charge to that of the ion itself. As a result, candies shrunk in the table salt solution!