If fire feeds off of oxygen(O), and there is oxygen in water (H2O), how does water extinguish fire?
In: Chemistry
ITT: Lots of people saying that the bonds between hydrogen and oxygen prevent water from being an oxidizer (as opposed to, say, HO, which is an oxidizer). But that’s not what puts out a fire.
Water has a vaporization temperature way lower than the temperature needed for combustion. Every time a water molecule vaporizes it takes energy from its surroundings. The combination of these two facts means that if you put a match into water, the intense heat gets absorbed by the vaporizing water, until the temperature of the match is too low to vaporize any more water, at which point the match has long since stopped burning.
This explains why dropping a match into water has the same effect as pouring water over top of it. Even if the water capillaries upwards a bit, it’s not effectively blocking oxygen to the match head. But it is drawing heat away very quickly and efficiently.
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