Mar
15
why does water put out a fire?
Filed Under Chemistry
Leroy J asked:
I know that water smothers the flames, but it has free oxygen in it, which is why fish can breathe water. This is different from what I am calling bonded oxygen. I checked around for the answer to this, but it was talking about the bonded oxygen atoms in a water molecule.
I know that water smothers the flames, but it has free oxygen in it, which is why fish can breathe water. This is different from what I am calling bonded oxygen. I checked around for the answer to this, but it was talking about the bonded oxygen atoms in a water molecule.
I hypothesized that the evaporative cooling effect of water would reduce a fuel’s temperature to below ignition temperature. But then I considered the case of throwing liquid oxygen on a bonfire. This would be extremely cold and evaporate very quickly, which would result in rapid heat loss. Yet I common sense tells me there would be a huge combustion.
Cheesus, let me clarify. I am asking why the FREE oxygen in water does not combust with wood.
Free oxygen is dissolved in the water, not bonded.
MOHAMMED
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LEONARD
Fire occurs when free oxygen combines with (oxidizes) another element (mostly Carbon), creating new molecules (like carbon dioxide) and energy in the process. The oxygen in water has already been ‘burned’ after it combines with hydrogen, creating energy and molecules of hydrogen dioxide, better known as water.
Another way of thinking about this is to understand that atoms lose their individual identities when they become parts of molecules. Sodium by itself reacts violently in contact with water. Chlorine is a poisonous gas. When a sodium atom and chlorine atom combine, however, they form a molecule of sodium chloride, also known as table salt.
RANDOLPH