======Diffusion in Hot and Cold Water======


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**Materials: **{{$demo.materials_description}}\\
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**Safety: **{{$demo.safety_description}}\\
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**Alternative titles:** Hot and Cold: Molecules in Motion
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====Summary====                   
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====Procedure====  
  - Fill one glass halfway with very cold tap water.  
  - Fill another glass halfway with very hot tap water.  
  - Predict how the food coloring will behave differently in hot and cold water.  
  - At the same time, add 2–3 drops of food coloring into each glass without stirring.  
  - Observe how the food coloring spreads in each glass. Compare the differences in diffusion rates.


====Links==== 
Demonstration - Hot & Cold Diffusion - Mr Z Physical Science: 
{{youtube>GXGfS0XA_Hg?}}\\
Food Coloring + Hot and Cold Water - Scott Milam: 
{{youtube>Z6PB7IKeHs4?}}\\
📄 Hot and Cold: Molecules in Motion - Liberty Science Center: [[https://lsc.org/news-and-social/news/hot-and-cold-molecules-in-motion]]\\



====Variations====
  * Heat or cool the food coloring itself in a water bath before adding it to water to see if its temperature affects diffusion.  
  * Compare results using salt water instead of plain water.  
  * Try the experiment with other liquids such as oil, vinegar, or juice to see if diffusion behaves differently.  
  * Test how stirring affects diffusion compared to letting it occur naturally. 


====Safety Precautions====
  * Adult supervision is required when handling hot water.  
  * Be careful not to spill water or food coloring on skin or surfaces.  
  * Clean up spills promptly to avoid staining.  
  * Pour water down the sink and wash glasses thoroughly after the experiment.



====Questions to Consider====
  * Why does the food coloring diffuse faster in hot water than in cold water?  
  * How does molecular motion explain the difference between hot and cold water diffusion?
  * How is diffusion important in the human body, for example in oxygen exchange in the lungs?  
  * Would the diffusion rate change if the water volume or container size were different?