======Ice Cube on a String======


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**Materials: **{{$demo.materials_description}}\\
**Difficulty: **{{$demo.difficulty_description}}\\
**Safety: **{{$demo.safety_description}}\\
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**Alternative titles:** Refreezing ice
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====Summary====                   
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====Procedure====  
  - Fill a glass to the top with water.  
  - Place an ice cube into the glass.  
  - Cut a piece of string longer than the width of the glass.  
  - Lay the string across the top of the ice cube. 
  - Sprinkle about half a teaspoon of salt onto the ice cube.  
  - Wait about 30 seconds.  
  - Gently lift the string. The ice cube should rise with it.



====Links==== 
How To Pick Up Ice with a String Experiment - Cool Science Experiments Headquarters: 
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Pick up Ice with a String Experiment | How does it work? - Hungry SciANNtist: 
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📄 Ice Cube on a String Experiment - Little Passports: [[https://www.littlepassports.com/blog/science/ice-cube-string-experiment/?srsltid=AfmBOoqOhxRR_R-WCP8QhIEvfJ5vB_pen27pg-mlgsGFNcYrveajiPLD]]\\


====Variations====
  * Try different amounts of salt to see how quickly the ice cube attaches to the string.



====Safety Precautions====
  * Safe for children with supervision—no hazards beyond handling ice.  
  * Avoid spilling water to prevent slipping.  
  * Dispose of melted ice water safely.




====Questions to Consider====
  * Why does salt make the string stick to the ice cube? (Salt lowers the freezing point, melting a thin layer of ice, which then refreezes around the string.)  
  * Why is salt spread on roads in winter? (To prevent ice from forming and make roads safer by lowering the freezing point of water.)  
  * What would happen if you tried this with sugar instead of salt? (Sugar does not lower the freezing point enough, so the string will not stick.)  
  * How is this experiment an example of a freezing point depression? (Salt ions disrupt the structure of ice, requiring a colder temperature to stay frozen.)