======Cracking Apart======


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**Materials: **{{$demo.materials_description}}\\
**Difficulty: **{{$demo.difficulty_description}}\\
**Safety: **{{$demo.safety_description}}\\
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**Categories:** {{$demo.categories}}
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**Alternative titles:** Thermal Weathering of Rocks, Physical Weathering
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====Summary====                   
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====Procedure====
  - Place a small granite chip in tongs and hold it in the outer blue flame of the Bunsen burner until it glows.  
  - Quickly transfer the hot chip into a beaker of cold water.  
  - Repeat the heating and cooling cycle several times until the granite chip begins to crack apart.  
  - Record the number of cycles required for the granite to fracture.  


====Links==== 
Granite - Physical weathering : effect of temperature change - ILC Science: 
{{youtube>FKJzeob_d5I?}}\\


📄 Cracking apart - Earthlearningidea: [[https://www.earthlearningidea.com/PDF/71_Cracking_apart.pdf]]\\



====Variations====
  * Compare weathering rates of granite with quartzite (single mineral).  
  * Investigate the effect of changing the temperature of the cooling water.  
  * Explore other physical weathering methods such as freeze-thaw cycles or wetting and drying.  




====Safety Precautions====
  * Safety glasses required.  
  * Handle hot rocks with tongs, never with bare hands.  
  * Keep hands and face away from the flame.  
  * Use a heatproof mat under the Bunsen burner.


====Questions to Consider====
  * How many heating and cooling cycles were needed for the granite chip to break apart?  
  * How does this laboratory simulation represent natural processes in deserts?  
  * Where on Earth today might rocks break apart in this way?  
  * In what ways is this laboratory activity different from real desert conditions?  
  * Why would granite (containing several minerals) weather more quickly than quartzite (containing one mineral)?