======Smelly Balloons======


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**Materials: **{{$demo.materials_description}}\\
**Difficulty: **{{$demo.difficulty_description}}\\
**Safety: **{{$demo.safety_description}}\\
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**Alternative titles:** Scented Balloons Diffusion Demo, Vanilla Balloon
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====Summary====                   
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====Procedure====  
  - Check for latex allergies in the class and choose alternative gloves/balloons if needed.  
  - Gather several scents (e.g., flavor extracts, essential oils, perfume, or a spice slurry) and choose distinct balloon colors—one color per scent plus one empty control.  
  - Using a clean dropper for each scent, place 3–4 mL of a single scent into a balloon, swirl to coat the inside, then inflate and tie it. Make two balloons of each scent if desired.  
  - Prepare additional balloons of other colors with different scents. Inflate one balloon with no scent to serve as a control.  
  - (Optional) Tie each balloon to a short string and tape to lab tables to keep them in place.  
  - Have students rotate among balloons, gently wafting near the nose (no squeezing), and record their best guess for each scent.  
  - Lead a discussion: How did the scent travel through the latex? Introduce diffusion, semi-permeable membrane, concentration gradient, and equilibrium.  




====Links==== 
Smelly Balloons - ASU Open Door: 
{{youtube>UMtmDCtgS64?}}\\

O Wow Moment: Smelly Balloons - Children's Museum Houston: 
{{youtube>rWdN91ysGZo?}}\\

📄 Introducing Diffusion with Smelly Balloons - Science Lessons that Rock: [[https://sciencelessonsthatrock.com/introducing-diffusion-with-smelly-balloons-html/]]\\


====Variations====
  * Compare diffusion using thick vs. thin balloons or different brands.  
  * Test water-based extracts versus oil-based scents to see which diffuses faster.  
  * Place balloons in warm versus cool rooms to observe temperature effects on diffusion rate.  
  * Time how long it takes before most students can correctly identify each scent; graph class data.  
  * Replace latex with non-latex balloons to accommodate allergies and compare results.




====Safety Precautions====
  * Screen for latex allergies; provide non-latex balloons if needed.  
  * Do not open or taste the scents; some extracts and essential oils can irritate skin or eyes.  
  * Use minimal amounts of strongly scented materials and maintain ventilation for sensitive students.  
  * Assign one scent per color and separate filling tools to avoid cross-contamination.  
  * Instruct students to waft odors rather than inhale directly from the balloon surface.





====Questions to Consider====
  * Why can odor molecules pass through latex while liquids remain inside the balloon?  
  * How does a concentration gradient drive diffusion, and what happens when equilibrium is reached?  
  * Which variables (balloon thickness, temperature, molecule size, solvent type) most affect diffusion rate, and why?  
  * What is the purpose of the unscented control balloon?  
  * How is this model similar to and different from diffusion across cell membranes (e.g., phospholipid bilayers, transport proteins)?