======Products of Combustion======


<WRAP right box>
**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:** Burning Hydrocarbons: Detecting Water and Carbon Dioxide
</WRAP>

====Summary====                   
{{$demo.summary}}



====Procedure====  
  - Assemble the apparatus with a funnel, tubing, and two boiling tubes—one containing cobalt chloride paper and the other half-filled with limewater.  
  - Connect the tubes so that air drawn by the pump passes first over the cobalt chloride paper, then through the limewater.  
  - Light the candle beneath the funnel so combustion gases are directed into the system.  
  - Turn on the pump to gently draw the gases through.  
  - Observe as the cobalt chloride paper changes from blue to pink (indicating water) and the limewater turns milky (indicating carbon dioxide).  
  - Optionally, repeat the setup without the candle to show that normal air does not produce the same rapid changes.



====Links==== 
Combustion Demo - CRRChem: 
{{youtube>_DkcsvP5M_M?}}\\

Year 10 Products of combustion - susanna wilkinson: 
{{youtube>8iCLrYDWiJ0?}}\\

📄 Identifying the products of combustion - Practical Chemistry: [[https://assets.ctfassets.net/pc40tpn1u6ef/file-14239/06ccf8c2ec55efed84c6ae5f2cfb095f/8492-Motr_vehicle_maintenance_teachers_notes.pdf]]\\


====Variations====
  * Burn alcohols such as ethanol using a spirit burner instead of a candle.  
  * Use a camera and projector to display the color changes to the whole class.  
  * Try comparing different hydrocarbon fuels to see if results vary.



====Safety Precautions====
  * Wear eye protection.  
  * Handle cobalt chloride paper carefully, as it is toxic, a sensitizer, and a category 2 carcinogen. Minimize handling and wash hands after use.  
  * Limewater (calcium hydroxide solution) is an irritant; avoid skin or eye contact.  
  * Ensure tubing near the flame is made of heat-resistant glass or properly joined to prevent melting.  
  * Use a stable candle such as a tealight to reduce fire hazards.  
  * Work in a well-ventilated area to avoid inhaling combustion fumes.




====Questions to Consider====
  * What elements are present in hydrocarbons such as candle wax? (Carbon and hydrogen)  
  * What products are formed when these elements burn in oxygen? (Carbon dioxide and water)  
  * Why is it important to compare the results with and without the candle? (To show the observed changes are due to combustion, not normal air content)  
  * How does the production of carbon dioxide relate to environmental issues such as the greenhouse effect? (Carbon dioxide is a greenhouse gas contributing to global warming)