“Too much oxygen things go boom” It means Oxygen can be used as fuel like a gas stove, or lighters, or that some mundane things like clothes/footwear can ignite from friction in a concentrated oxygen room?

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“Too much oxygen things go boom” It means Oxygen can be used as fuel like a gas stove, or lighters, or that some mundane things like clothes/footwear can ignite from friction in a concentrated oxygen room?

In: Chemistry

Oxygen feeds fire, so the more oxygen the more the fire will burn, and more intensely. However, you’d still need a spark to ignite it. The friction from clothes etc. would not produce a spark to ignite the oxygen. However, mundane things like plugging a plug into a socket could ignite the oxygen, and any conventional way of creating a spark would also have that effect.

Too much oxygen means that things we don’t normally think of as explosive or even flammable, things like metal, can burn or explode.

Stuff burns because it combines with oxygen. Normally, air is only 20% oxygen, and the more oxygen you provide, the easier and faster it burns.

If you use pure oxygen at high pressure, heavy oils that normally needs a flame to ignite and burn calmly, explode with only a little friction. Steel or brass, which we don’t think as flammable, ignites with only gentle heating.

And soaking something flammable in liquid oxygen turns it into an explosive. There is plenty of oxygen, and it is in close contact with the fuel – provide a source of ignition and the two will combine rapidly.

Combustion (fire) requires two things: fuel (wood, gas, coal, etc…) and oxidizer (usually oxygen). The more concentrated one thing or the other, the easier (and faster) it is for a reaction to occur. That means things burn a lot more easily when there’s more concentrated oxygen, but the oxygen won’t burn all by itself.

Most of what we think of as explosions (other than nuclear) is the very rapid burning of some substance, which releases a lot of energy quickly resulting in expansion of the surrounding gases.

Burning (mostly, but not exclusively) consists of something combining with oxygen releasing heat energy. Normal atmosphere is about 20% oxygen and when we burn wood, lighter fluid, petrol (in car engines) we mostly rely on that 20% oxygen and 80% nitrogen mix in air. In many cases the rate of burning is limited by the amount of oxygen available – which is why blowing air is useful when starting a campfire – you increase the amount of oxygen and remove the gaseous byproduct of burning which already consumed the available oxygen.

If you increase the oxygen concentration, then things burn faster – ie releases heat faster. So something that might burn in a controlled fashion in normal air, might burn so fast that it heats the surrounding air so quickly that a compression wave forms (and that is what makes an explosion)

But you need to understand that these things are a combination of something with oxygen. So both are needed. Pure oxygen with nothing else doesn’t burn or explode. Explosives are usually a mix of compound and one of the compound in the mix usually produces oxygen when heated. So an explosive provides both the fuel and the extra oxygen at the same time allowing it to burn so fast that it causes the explosion.

Fire is fuel reacting with oxygen. The fuel molecules combine with the oxygen molecules in a reaction that releases heat. For such a reaction to take place, an oxygen molecule needs to bump into a fuel molecule, and the reaction also needs a little bit of heat to get going. After that initial heat, the fire can keep itself going by producing more heat with each reaction. But that does mean you need the reactions to keep happening. It’s not enough to get one fuel molecule to react with one oxygen molecule. If there aren’t other fuel and oxygen molecules nearby, the heat from that initial reaction just spreads out into nothing. So to keep a fire going, you have to supply fuel and oxygen. The more you have of each, the easier it is for the fire to keep going and even grow.

When a fire grows very quickly, that’s called an explosion. Each fire reaction produces hot gas (mostly steam and CO2). Many fire reactions happening at the same time creates a lot of hot gas. That hot gas is bigger in volume than the fuel and the oxygen were. It needs more room than the fuel and oxygen did. So it expands outwards with great force and speed. “Boom”, as it were.

Usually fire gets its oxygen from the air in the atmosphere. This air contains only about 20% oxygen, while the rest is mostly nitrogen. For some fuels, this means that they cannot explode. The 20% just isn’t enough to get enough fuel and oxygen molecules bumping into each other to spread the fire quickly enough. But with more oxygen, you get more fuel-oxygen collisions. Now suddenly the same fuel can burn much faster and create an explosion. And fuels that were already explosive only get explosive-er.

Ok…I’m going to go more basic…

In order for you to have FIRE you need 3 things…

1). A spark, something to start the fire

2). You need a fuel (Wood, paper, anything else flammable)

3). Oxygen

If you remove ANY of those 3 things there can’t be fire

As an example, if you had a 100% oxygen filled room and had a way of generating a spark in that room, nor there wasn’t anything flammable in the room, there wouldn’t be a fire.

Or

You have a stack of paper in a room that you then pump full of oxygen, you still won’t have a fire

Or

You could have a spark in a room filled to the brim with sawdust, but sealed in a hard vacuum and you still won’t have a fire

You need 3 things for a fire (explosion is just very fast burning)

Fuel + Oxygen + spark

The more you add of one thing, the less you need of the others to make fire happen.

The more flammable something, the less oxygen and spark you need (think gasoline vs wood, it takes more effort to get wood to burn)

The more oxygen you have, the easier it is to get stuff to burn. That’s why welding with oxygen often has flames on the steel.

And the more “spark” you have, the easier it is to get stuff ignited. The spark from an airplane is enough to get an office fire going which is enough to weaken steel beams to the point of crashing a skyscraper to the ground.

Also, the point of a wick is to focus the spark to make only one particular spot burn, which reduces the amount of energy needed to get the fire started.

Bonus fact. Explosives such as gunpowder contain stuff like Nitrate which already has oxygen in it, so it has more. That’s why it explodes, it has a lot of oxygen without being exposed to the air.