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Stay-at-home science project: Enlarge gummy bears to reveal the secrets of osmosis
By Rachel Feltman
Posted on May 4, 2020
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Welcome to PopSci’s at-home science projects series . On weekdays at noon, we’ll be posting new projects that use ingredients you can buy at the grocery store. Show us how it went by tagging your project on social media using #popsciprojects.
Gummy bears are delicious. That’s not up for debate (though you’re welcome to eat a few to prove the hypothesis). But they’re also the perfect critters to help demonstrate a process that makes life as we know it possible: Osmosis.
Believe it or not, osmosis also happens when you drop gummy bears into water, revealing the most basic inner workings of your body’s cells. Just add water and a spoonful of salt to see it happen before your eyes.
- Time: 5 minutes of prep, and 3 to 9 hours of waiting
- Difficulty: easy
What you’ll need
- Gummy bears, preferably dark in color
- Three small bowls
- 2 tablespoons of salt
- (Optional) Ruler
- (Optional) Kitchen scale
Instructions
1. Fill two of your bowls with cool water. Room temperature is fine, but keep away from hot water—it’ll melt your gummy bears.
2. Add the salt to the first bowl. The second should just contain water.
3. Plop one gummy bear into each bowl. Make sure they’re fully submerged. Leave the bowls somewhere they won’t be disturbed. Gummy bears are tempting—even when they’re salty and soggy!
- Note : We tried different types of gummies (including the sour kind coated with mouth-puckering crystals), and we came to the conclusion that the ideal gummy bears for this experiment are dark in color and chewy instead of soft—just the classic gummy bear . A darker color will not dilute so much as to turn the gummy bear totally clear as it absorbs water, and the thicker gelatin mixture will make the candy less likely to fall apart when you take it out for observation. Also, stay away from sour gummies and those with unusual flavor additives, since they are less likely to yield the intended results.
4. Set aside a third gummy as your experimental control. We recommend you do this before you even think about eating the rest of your gummy bears. It’d be tragic to suddenly realize you ate them all and you no longer have a control for your experiment. Keep it dry.
5. Wait for three hours.
6. Check back in on your waterlogged candies. You can scoop them out with a spoon and observe them on a paper towel if you so choose, but be sure to return them to their proper bowls. Take note of how the gummies have changed—write down your observations so you can contrast them with the end results. You can check in again after the next three hours.
7. (Optional) Take some measurements. If your little experimenters need more of a challenge, you can have them measure the bears with rulers and/or kitchen scales, and calculate just how much size and mass the bears have lost or gained.
8. Wait another six hours. The full transformation should be complete around hour nine.
9. Retrieve your bears from their bowls. Use a small spoon and line them up on a plate or paper towel to see how much they’ve changed. The gummy in plain water should be much larger than the unsoaked candy, while the salted water should have kept its bear roughly the same size—unless it’s caused it to shrink. More on that later.
10. Fill a third bowl with cool water and a tablespoon of salt. Place the expanded, waterlogged gummy bear into it and observe it every few hours. It should get noticeably smaller as it soaks.
How it works
Osmosis is the movement of water through a semipermeable membrane—that is, a material with holes large enough to let some things in, but small enough to keep others out. In this process, water moves through the membrane without force or energy, to make water concentration versus other molecules roughly the same on either side.
This process is important in keeping us alive. The outer membrane of our cells is semipermeable and allows small molecules like water and oxygen to pass through while keeping all the cell’s organelles protected and in place. When it’s time to eliminate waste, the cell will start pushing the toxic molecules out, while absorbing water from our blood through osmosis. Once the cell has balanced its water concentration to the one outside of it, it will stop taking in more liquid, thus preventing the cell from bursting.
Gummy bears are made of gelatin and sugar, and the proteins that make up gelatin are very similar to the outer membranes of our cells. Just like them, the gummy bear’s gelatin “skin” will allow water and other small molecules to pass through while keeping larger ones contained—in this case, those larger molecules are the sugar that make gummy bears taste so good.
When you place a gummy bear into water, the sugar molecules will try to spread out and disperse evenly through the water bowl. But the gelatin membrane won’t let them out. That sugar also makes the gummy have a relatively low concentration of water compared to the liquid around it. Osmosis seeks to correct this imbalance, so water will keep pushing into the gummy and through the membrane until the concentration is the same on either side of the gelatin. This means your gummy is going to absorb lots and lots of water.
In a solution of water and salt, the bowl and the bear have similar water concentrations, so the candy may stay about the same size or even shrink, if the water is salty enough. Just as the sugar in the bear lowers its water concentration, the salt in the bowl means a lower ratio of water to other molecules. As a response, the bear may push out water in order to dilute the liquid inside the bowl. If you place the water-swelled bear into a salt solution, those extra water molecules will leave the bear to lower the salt concentration in the bowl.
If you have time (and gummies) to spare, you can elaborate on this experiment by testing different salt concentrations. You can line up several bowls with increasing quantities of salt in the same amount of water. The more salt you add, the more your candy should shrink.
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Gummy Bear Experiment
Osmosis can be a difficult concept for kids to understand. I’ve always found that visual explanations really hit home with kids and help them to understand. Today we have a growing gummy bear experiment that is a perfect compliment to our Gummy Mummy experiment that explores the science of desiccation and diffusion. Because gummy bears are made of gelatin they will not dissolve in water like other candy will. They will however absorb liquids and change in shape and size. We’ve set up an experiment with four different liquids to see the difference in how the gummy bears are able to absorb each and how they change over the course of the day.
Great Growing Gummies – Gummy Bear Osmosis Experiment
Table of Contents
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What is Osmosis?
Scientifically, Osmosis is when solvent molecules (usually water) cross a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration. This creates equilibrium between the solute and solvent, balancing the concentration of solutes on both sides of the membrane. Osmosis is a passive process in that it requires no energy from the cell to occur.
Now – that’s a lot of big words and concepts so let’s break down that vocabulary:
Solvent : substance able to dissolve other substances. Solute : a dissolved substance Membrane : a thin, soft flexible sheet or layer especially of a plant or animal part Semi-Permeable Membrane : a membrane that only allows certain substances to pass through. Concentration : the amount of a component in a given substance. Equilibrium : a state of adjustment between opposing or divergent influences or elements
Gummy Bear Osmosis Lab
Gummy Bears Small Clear Bowls or Jars Water Sparkling Water White Vinegar Oil
I like to start this in the morning so you can check on it throughout the day and see the changes in the gummy bears.
STEP 1: Lay out four bowls on the table and put a gummy bear in each bowl. Then beside each bowl put another gummy bear of the same color so you can compare the two easily over the course of the day.
STEP 2: Measure equal amounts of each of your solvents. We used a quarter of a cup of water, sparkling water, white vinegar and oil and poured them over the gummy bears in the bowl.
STEP 3: This is a great time to have a discussion about osmosis and have your kids make predictions about what they think is going to happen in each bowl and why. What effect might each substance have on the gummy bear? Have the kids write down their predictions.
STEP 4: Set a timer for an hour and let the bears do their thing.
STEP 5: Check back each hour for the rest of the day and write down observations over the course of the day.
Gummy Bear Osmosis Experiment Results
Now the exciting part… the results of our experiment! Let’s take a look at the results individually first.
When gummy bears are soaked in water the bear will swell and grow in size. This is because the water will flow into the gummy bear through its semi-permeable membrane. The sugar molecules try to spread and dissolve but they can’t get out of the gelatin so they expand resulting in the gummy bear expanding.
Sparkling Water
Will have a similar result to water. The only difference is that the addition of carbon dioxide to the water can have an acidic effect on the bears which would cause the outside to soften allowing more water to be able to pass through the bear and it swells up more. You will also be able to observe the carbon dioxide bubble sticking to the outside of the bear.
White Vinegar
White Vinegar will have an acidic reaction with the gummy bear softening the outside of it, however the liquid is not as easily absorbed into the bear as water so the gummy may get softer but will not change in size as much as the bears soaked in water.
Because oil is polar it doesn’t mix well with water or other substances. The oil will have very little effect on the bears and you will not see much change if any at all. This gummy bear will also retain its color the best because the oil isn’t breaking down the bear or being absorbed into it so the structure and color will remain the same.
Comparing the Results
The most fascinating part of this experiment is comparing the results of the different solvents. Set the gummy bears out side by side with their controls so you can visually see the differences.
To get really scientific with your results, which is perfect for your older kids or kids needing more of a challenge, have them weigh and measure the gummies and compare results with the controls and each other.
You can also dissect the gummy bears and view them under a microscope to look for microscopic changes.
Extension Ideas
I think your kids will love this Gummy Bear Lab experiment on Osmosis! Encourage your students to get creative and add other variations like adding things like salt or baking soda to the water to see if it changes the results. Or try other solvents.
Want more osmosis experiments? Try this Rainbow Water Beads Experiment or the Bouncy Egg Experiment which involves a chemical reaction and osmosis.
Want more gummy science? Check out our Gummy Mummies . Or make your own gummies! You can check out these recipes on the site: Valentine’s Day Gummies , Star Wars Gummies , Rainbow Dragon Egg Gummies .
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