Diffusion is a topic that is covered in biology (when we introduce cell membranes) and chemistry (particle movement and kinetic theory). I came across this "smelly balloons" activity on Flinn's website and thought it was such a fun way to introduce diffusion. In this activity, students will smell balloons that have different flavor extracts inside. Their task is to guess the scent and explain particle movement. How is the smell passing through the latex barrier? (Note: Prior to this activity you will need to make sure none of your students have latex allergies. Bust out those lab safety contracts they signed at the beginning of the year!)
For this activity you will need:
- Balloons (an assortment of colors is ideal)
- Eyedroppers or pipettes
- A variety Flavor extracts* or different odor substances
- String and tape (optional)
*Flinn's directions say to use a variety of flavor extracts. Flavor extracts can be pricey, so if you don't have very many at home you have some other options. You can use essential oils, perfume, or cooking spices. I used vanilla extract, lemon extract, eucalyptus oil, and cinnamon (mixed with a little bit of water to make a slurry).