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Name: George
Status: other
Age: 40s
Location: N/A
Country: N/A
Date: 2000


Question:
I was explaining to my neice the other day that a fire requires oxygen in order to burn. She asked the question: "If a fire requires oxygen atoms in order to burn then how is it that water (which has 1 oxygen atom for each 2 hydrogen atoms) will extinguish a fire"?


Replies:
When something burns a spontaneous chemical reaction is occurring. When a spontaneous reaction occurs energy is released and the products are more stable than what you start out with. Water and carbon dioxide are the products of the combustion of most materials. The oxygen in water has already "burned" and is no longer available to cause something else to burn.

When you put water on a fire it does two things. It displaces the free oxygen molecules (which have two atoms of oxygen) so that it is not available to participate in the burning process AND it turns to steam, carrying heat away from the fire, cooling it to the point where it can no longer burn.

Dr. Bradburn



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