Fire and Water are the same!

Water (H₂O) is a fire extinguisher, while hydrogen (H₂) is good fuel and oxygen (O₂) is good oxidizer. Why?

 

This is a great question that reveals the fascinating chemistry behind fire and water. In this blog post, I will explain why water can put out most fires, while hydrogen and oxygen can make them more intense.

 

Fire triangle

Fire is a chemical reaction that involves the rapid oxidation of a fuel, which means that the fuel combines with oxygen and releases energy in the form of heat and light. For example, when you light a candle, the wax (which is mostly made of carbon and hydrogen atoms) reacts with the oxygen in the air and produces carbon dioxide, water vapor, and heat.

Second stage rockets of space shuttle use liquid oxygen and liquid hydrogen as fuel. 

However, not all fuels and oxidizers are equally effective at creating fire. Some fuels, like hydrogen, have a high energy content and can release a lot of heat when they react with oxygen. Some oxidizers, like pure oxygen gas, have a high affinity for electrons and can make the fuel burn faster and hotter. That's why hydrogen and oxygen are often used as rocket propellants, because they create a powerful thrust when they combust.

 Water, on the other hand, is a very stable molecule that has a low energy content and a low affinity for electrons. It is already the product of a combustion reaction between hydrogen and oxygen, so it cannot react further with either of them. That's why water can act as a fire extinguisher, because it does two things: it cools down the fuel and the flame, and it blocks the oxygen from reaching the fuel.

 When you spray water on a fire, you are transferring heat from the fire to the water, which lowers the temperature of the fuel and the flame. If the temperature drops below the ignition point of the fuel, the fire will go out. Also, when water hits the fire, it turns into steam, which expands and pushes away the oxygen from the fuel. Without oxygen, the fuel cannot continue to burn.

 Of course, water is not effective against all types of fires. Some fuels, like metals or oils, have higher ignition points than water's boiling point, so water cannot cool them down enough to stop the fire. Some fuels, like sodium or magnesium, can react with water itself and produce flammable gases like hydrogen or methane, which can make the fire worse. Some oxidizers, like chlorine or fluorine, can provide their own oxygen source and do not depend on the air for combustion. These types of fires require special fire extinguishers that use different chemicals or methods to put them out.

Various types of fire extinguishers and their application.

To summarize, water (H₂O) is a fire extinguisher because it is a stable molecule that cannot react with most fuels or oxidizers. It cools down the fire and blocks the oxygen from reaching the fuel. Hydrogen and oxygen are good fuel and oxidizer because they have high energy content and high affinity for electrons. They react quickly and intensely to produce heat and light.