======Wafting Demonstration with Ammonia======


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**Materials: **{{$demo.materials_description}}\\
**Difficulty: **{{$demo.difficulty_description}}\\
**Safety: **{{$demo.safety_description}}\\
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**Alternative titles:** Safe Smelling in the Laboratory
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====Summary====                   
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====Procedure====  
  - Soak a piece of filter paper in phenolphthalein solution and allow it to dry in a fume hood overnight.  
  - Swirl a bottle of ammonium hydroxide gently to build pressure.  
  - Open the bottle slowly to release ammonia vapor.  
  - Hold the dried filter paper with forceps and pass it above the mouth of the bottle.  
  - Observe the filter paper turn pink as ammonia vapor diffuses into it.  
  - Demonstrate the wafting motion with your hand to show how odors should be tested safely.



====Links==== 
Wafting - Josh Thomas: 
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📄 Waft It — Don’t Sniff It! - Flinn Scientific: [[https://www.flinnsci.com/api/library/Download/47890af9c0ad488c955c2671f48b1dbb?srsltid=AfmBOormNn8d0MNPFIjY8Twl06o9orcuRTYlyKn5xcG4twkpM-prRdyH]]\\


====Variations====
  * Try using other pH indicators (e.g., universal indicator paper) to detect ammonia vapors.  
  * Place treated paper at different heights above the bottle to demonstrate diffusion.  
  * Compare ammonia with other safe household vapors (e.g., vinegar) to illustrate differences.



====Safety Precautions====
  * Ammonium hydroxide vapors are highly irritating and toxic - never inhale directly.  
  * Wear chemical splash goggles, gloves, and a lab apron.  
  * Conduct the experiment in a fume hood or well-ventilated area.  
  * Handle phenolphthalein solution with care; it is flammable and moderately toxic.  
  * Dispose of waste materials following appropriate chemical disposal guidelines.




====Questions to Consider====
  * Why is it dangerous to sniff chemicals directly? (Some vapors are toxic or can damage nasal passages.)  
  * What is the purpose of wafting? (It allows controlled detection of an odor while minimizing exposure.)  
  * Why does the phenolphthalein paper turn pink? (Ammonia vapor dissolves in the moist paper, raising the pH and causing the indicator to change color.)  
  * How does molecular weight affect gas diffusion? (Lighter gases diffuse faster through air than heavier ones.)