EIS 8: Diffusion and Osmosis
This activity will give you the opportunity to see diffusion and osmosis at work, right from your own kitchen!
Materials
- Approximately ½ cup of warm water. We recommend heating a glass of water in the microwave for 30 s to 1 min, or heating water using a kettle.
- Approximately ½ cup of cold water. We recommend adding an ice cube or two and waiting for it to melt.
- Approximately ½ cup of room temperature water.
- Approximately ½ cup of rubbing alcohol, another clear alcohol, or acetone (nail polish remover).
- Approximately ½ cup of corn syrup or simple syrup. Simple syrup can be made by boiling sugar in water.
- Clear containers/cups/glasses for each of the above liquids.
- Food coloring
- Stopwatch (an electronic one, for example on your phone, will work)
Table
You may want to print off and use this table to help you record your results. If you don't have a printer, copy something like it in your workbook.
| Table 1 for EIS 8 |
Procedure
1. Set up each of your 5 glasses of liquid and be sure you know which is which. Have your food coloring and stopwatch handy.
2. Start the stopwatch as you add 1 drop of food coloring to the warm water.
3. Measure the time that it takes for the food coloring to completely diffuse in the water (until the entire solution is a uniform color). Stop your stopwatch.
4. In your table, record the time that it took for the food coloring to diffuse completely, along with any other observations you might have had.
5. Repeat steps 2-4 for the remaining liquids.
2. Start the stopwatch as you add 1 drop of food coloring to the warm water.
3. Measure the time that it takes for the food coloring to completely diffuse in the water (until the entire solution is a uniform color). Stop your stopwatch.
4. In your table, record the time that it took for the food coloring to diffuse completely, along with any other observations you might have had.
5. Repeat steps 2-4 for the remaining liquids.
Bonus Activity: Diffusion Across a Semipermeable Membrane
Note: This activity is not required, as not everyone has the supplies (iodide solution) readily on hand. However, iodide tincture can be acquired relatively cheaply at most drug stores, and it can be cool to see diffusion at work in this activity!
Materials
- About 1 cup of water. Room temperature or slightly warm is best.
- 1 tbsp of cornstarch.
- 10 drops of iodide tincture. This can be acquired relatively cheaply at most drug stores. You do not want “decolorized” iodine tincture—we want to be able to see the color moving.
- A plastic baggie. Thin, plastic sandwich bags work well. Thicker, freezer-safe bags do not work as well, but you may still see the effect. Plastic wrap will also work but may require some finessing to get it to hold water. The bag should be water-tight.
- A clear cup/glass.
Procedure
- Put about ½ cup of water and 1 tbsp of cornstarch in the sandwich bag and seal it shut.
- Put about ½ cup of water in the glass.
- Put the filled sandwich bag of water in the glass, being careful not to spill.
- Put 10 drops of iodide solution in the water in the glass. Watch how the dye moves. You should see it crossing into your plastic baggie.
If you’re having fun, we’d love to see your experiments at work! If you have an Instagram and the permission of your relevant responsible adult, share a photo or video with us @eons_learning, #DiffusionEons.