Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Saionji on August 29, 2010, 06:03:00 PM
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Why the firefighters add agents surfactants in water to delete certain types of fire? I think that some properties of tension are changed, but I do not understand how it ocurrs and how could help.
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What is needed to sustain a fire?
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High temperatures, is formed in reaction exothermic oxidation and by this require an activation energy...sorry, what is?
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Essentially a fire needs three things to keep going.
1) Heat
2) Fuel
3) Oxygen
If you put out a fire, you're doing so by taking out one of those criteria.
As examples, water reduces temperature. Cover a small fire with a glass and the oxygen burns up.
What might a surfactant do?
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Help on the solubilization and on the dispersion of phases ?
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I don't know what the assignment was but I can't imagine they are looking for something like that (albeit I dont really know what you mean there).
What I meant is, does adding a surfactant lower the temperature so the reaction can't keep going? Does it somehow interfere with the reactants so they can't be used? Does it displace oxygen? Use oxygen?
There are three aspects of fire, 1) fuel 2) oxygen 3) heat. A surfactant must effect one or more of those. Which ones could a surfactant effect? Start there imo.
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Only fuel?
-If the surfactant is added to water, the water will become more stabilized
-when the water get contact with the fuel, the interations and forces in a water will be different of some manner
-heat you mean temperature? I believe that when the water had interaction with the fuel, the fuel will therefore interact differently with the oxygen, and if it stop burns the temperature will decrease faster.
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What happens to water with surfactant added? In a bath? When washing?
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What happens to water with surfactant added? In a bath? When washing?
You mean " what happens to surfactant with water added?" Sorry, I found nothing about it, I do not know really what happens...
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No, I mean exactly what I wrote, and you know perfectly well what is happening, unless you are trying to say you have never washed nor bathed.
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If is not a quimical answer, can I say that bubbles are formed? When the water get contact, can I say that the water dissolve the surfactant and the mixture formed is sticky?
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It has nothing to do with solution sticky, but you are finally getting somewhere. Bubbles mean foam. Think about foam and three aspects of fire.
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The foam should hinder the movement of oxygen to let the system isolate? In the fire should ocurrs an emotion between water and fuel and surfactant agent, for this the movement of oxygen and vapors will be affected?
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The foam should hinder the movement of oxygen
Yes.
to let the system isolate? In the fire should ocurrs an emotion between water and fuel and surfactant agent, for this the movement of oxygen and vapors will be affected?
No idea what you are trying to say :o
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In the contact water/fuel happens an emulsion. The movement of oxygen and vapors produced will be hinder, affecting the burning of oxygen.
My english is bad
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I think basically what you are saying is it will stop oxygen from reaching the fuel?
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Yes.
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Then yeah. They also cool the fire too.
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So was it, since the beggining I thought that was a long and complex answer. Is possible explain more detailed what happens, the processes...?
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You an explain anything in more detail basically but why over complicate it? The process is, you're removing a reactant. It's turning into a limiting reagent problem :P