Gummy bear osmosis
01 // Question
How does the type of liquid a gummy bear soaks in change its mass overnight?
Gelatin candy works like a simple cell membrane model — it lets water pass through but not sugar.
02 // Variables
Independent
Liquid the gummy bear soaks in- Distilled water
- Salt water (about 10%)
- Vinegar
Dependent
Change in gummy bear mass- Grams, to 0.01 g
- Percent change
03 // Hypothesis
IF a gummy bear soaks in plain water instead of salt water, THEN it will gain more mass, BECAUSE water moves toward the side with more dissolved solids, and the bear itself has more dissolved sugar than plain water.
04 // Procedure
1. Weigh dry bears
Weigh one gummy bear per cup and record its starting mass to 0.01 g.
2. Pour the liquids
Fill each labeled cup with 100 mL of its liquid — water, salt water, or vinegar.
3. Soak overnight
Drop one bear into each cup and let them sit undisturbed for 12 to 24 hours.
4. Blot and reweigh
Lift each bear out with a spoon, blot gently on a paper towel, and weigh again.
5. Calculate the change
Find the mass change and percent change for each bear.
05 // Data table
| Liquid | Start (g) | After soak (g) | Change (g) | % change |
|---|---|---|---|---|
| Distilled water | ____ | ____ | ____ | ____ |
| Salt water | ____ | ____ | ____ | ____ |
| Vinegar | ____ | ____ | ____ | ____ |
Formula % change = (mass after − start mass) ÷ start mass × 100
06 // What to expect
The bear in plain water swells the most, because gelatin has more dissolved sugar than plain water, so water moves in through osmosis. The bear in salt water swells the least, or can even shrink, because salt water has more dissolved solids than the bear does.
The vinegar bear often gets soft and slightly dissolved at the surface, since the acid starts to break down the gelatin itself, not just move water across it.
07 // Lab notes
- Use bears from the same bag and pick a consistent color, since bag position and size can vary the starting mass.
- Don't leave bears soaking longer than 24 hours — they start to dissolve and fall apart, which throws off the mass reading.
- Blot each bear the same way before weighing, so leftover surface liquid does not add extra mass to the reading.
- Safety. This lab uses food-grade materials only. Wash hands before and after, but there is no real chemical hazard.
08 // Remember
Water moves toward the side with more dissolved stuff. A gummy bear is basically a sugar sponge.
09 // Questions people ask
Why does a gummy bear grow bigger in water?
A gummy bear's gelatin contains a lot of dissolved sugar. Since plain water has almost none, water moves into the bear through osmosis to even out the concentration on both sides of the gelatin's surface.
Why does a gummy bear shrink in salt water?
Salt water has a higher concentration of dissolved solids than the inside of the bear, so water moves out of the bear into the salt water instead, causing it to shrink or gain much less mass than the water sample.
What is the independent variable in the gummy bear osmosis lab?
The type of liquid each bear soaks in — usually plain water, salt water, and sometimes vinegar — is the independent variable. The dependent variable is the bear's change in mass.