Dropping a gummy bear into a glass of plain water and leaving it overnight transforms the familiar sweet into a science experiment. This common kitchen curiosity yields a dramatic physical change, turning the small, firm candy into something entirely different. The process highlights natural forces at work, using the candy’s unique composition as a model to explore how certain materials interact with water.
The Visual Transformation After 24 Hours
After 24 hours of submersion, the gummy bear undergoes a radical visual change. The candy swells dramatically, typically growing to two or three times its original size. This increase in volume is accompanied by a significant change in appearance, as the dense, vibrant color becomes noticeably paler and more translucent.
The texture shifts from a firm, resilient chewiness to a soft, squishy, and gelatinous consistency. While the original shape is retained, the enlargement makes the candy appear distorted and fragile. If removed, the swollen bear feels saturated, heavy, and easily breakable with minimal pressure.
Understanding the Scientific Mechanism
The dramatic swelling results from osmosis, the movement of a solvent across a semi-permeable barrier. Gummy bears are made primarily from sugar, corn syrup, and gelatin. The gelatin forms a network of protein fibers that acts as this semi-permeable membrane, allowing small water molecules to pass through while trapping larger sugar molecules inside.
The concentration of solutes (dissolved sugars) is extremely high inside the candy compared to the surrounding plain water. This difference creates a concentration gradient. To equalize this concentration, water molecules move from the area of high water concentration (the pure water) into the candy.
This inward flow of water causes the gelatin matrix to expand and stretch. The candy swells because it is absorbing water to dilute the concentrated sugars within its structure. The process continues until the physical structure of the gelatin can no longer stretch to accommodate the increased volume.
Experimenting with Different Liquids
The outcome changes dramatically when the liquid variable is altered, further demonstrating osmosis. When the gummy bear is placed in a hypertonic solution, such as water heavily concentrated with salt or sugar, swelling is greatly reduced compared to plain water. This occurs because the surrounding liquid already contains a high level of solutes, lessening the concentration difference between the candy’s interior and exterior.
In a highly concentrated salt solution, the gummy bear may even shrink slightly as the osmotic gradient reverses. If the salt concentration outside is greater than the sugar concentration inside, water moves out of the bear to dilute the solution, causing the gelatin matrix to contract. Conversely, placing the gummy bear in a non-polar liquid like cooking oil results in virtually no change, as oil molecules do not interact with the gelatin or participate in osmosis.