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/* TITLE - Required                                                                                    */
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======Dry Ice pH Colour Change======


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/* GREY BOX INFORMATION - Required                                                                     */
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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:** Dry Ice and Universal Indicator
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====Summary====                   
{{$demo.summary}}


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/* PROCEDURE - Optional                                                                                */
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====Procedure====  
  - Fill a beaker or container with water and add several drops of universal indicator.
  - Using gloves or tongs, add chunks of dry ice.
  - Watch as the solution bubbles, fog forms, and the color changes from green to orange as carbonic acid forms.



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====Links==== 
Description or Video title - Author: 
{{youtube>SOecE4EdjxM?}}\\
📄 Description or Title - Author: [[https://www.link.link]]\\
🎞️ Description or Video title - Author:: [[https://www.youtube.com/watch?v=Kou7ur5xt_4]]\\


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/* VARIATIONS - Optional                                                                               */
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====Variations====
  * Add a small amount of 0.1 M sodium hydroxide (NaOH) before starting to make the initial colour of the universal indicator purple.
  * Add more concentrated sodium hydroxide once finished to get the solution back to a purple colour.
  * Use different acid–base indicators to observe alternate color changes.


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/* SAFETY PRECAUTIONS - Required                                                                       */
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====Safety Precautions====
  * Always wear gloves or use tongs when handling dry ice to avoid frostbite.
  * Wear goggles and a lab coat when working with strong bases (sodium hydroxide).
  * Use only small amounts of concentrated sodium hydroxide and handle with care - it is corrosive.
  * Conduct in a ventilated space, since sublimating dry ice releases carbon dioxide gas.
  * Keep dry ice and sodium hydroxide away from children and pets.


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====Questions to Consider====
  * Why does dissolving carbon dioxide make the water acidic?
  * How does the universal indicator show the gradual change in pH?
  * Why does the fog flow over the edge of the beaker instead of rising?
  * How does adding NaOH reset the solution back to purple?


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/* DEMONSTRATION INFORMATION - Required                                                                */
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/* Complete information in the Demonstration Info box below, following instructions exactly. */