What Fire Actually Is? And How It's Work?

What Fire Actually Is? And How It's Work?

In the mid of 1800s, Michael Faraday gave a series of Lectures for kids at the Royal Institution in London, and one of his favourite subjects to talk about was "Fire".

Actually, Michael Faraday was particularly interested in candles, because in their delicate flames, they told some interesting lessons on how fire really works?

chemical equation of fire

You might seen fire described like this (CH4 + 2O2 = CO2 + 2H2O) in your chemistry class, but a chemical formula doesn’t explain, what fire is in actual?

It sounds like a recipe explains what chocolate chip cookies, taste like.

So Now, Talk About What Fire Actually Is?

What Fire Actually Is?

If you look at the flames of fire, the flames are obviously not solid, nor are they liquid.

It's mingling with the air, more like a gas, but more visible and more fleeting.

But, at the scientific level, fire differs from gases. 

Because gases can exist in the same state, while fires always burn out.

Is Fire "Plasma"?

Actually this is the misconception, that fire is a plasma. 

fire isn't a plasma

The fourth state of matter, in which electrons are stripped of by their atoms.

Actually, like fire and unlike other kinds of matter, plasma don’t exist in a stable state.

Plasma only forms, when gas is exposed to an electric field or super heated to temperatures of thousands or tens of thousands of degrees.

So Now, If fire Isn’t A Solid, Liquid, Gas or Even Plasma. What Is It?

fire Isn’t A Solid, Liquid, Gas or Even Plasma

It turns out, actually fire isn’t matter at all.

fire is a sensory experience of a chemical reaction called Combustion.

Instead of that, it’s all our sensory experience of a chemical reaction called Combustion.

So After All Of This, Now Talk About It's Flame.

So, The first thing, we notice about a flame is all those different colours.

Hot things glow due to "Black body radiation".

And, if we look closer, at the bottom of the flame, it’s hotter(around 1000-1400 C), so it glows blue, and in the middle it’s little cooler(around 800-1000 C), so it glows yellowish-orangish.

Inside of that flame, hundreds of chemical reactions taking place

Actually, Inside of that flame, hundreds of chemical reactions taking place.

oxygen, carbon and hydrogen needs heat to start fire

The oxygen in the air. And, the carbon and hydrogen ( or hydrocarbons ) in the candle. Actually don’t do anything on their own. 

Actually, It takes a little outside heat to get fire started. 

What Is Essential For Fire Except Fuel, Oxygen And Heat?

Now, before fuel starts burning. There is a process, where Solid fuel is vaporised by the heat and ripped into smaller chunks. And this process is called "Pyrolysis", and actually, you can’t have a flame or fire without this.

dark cone into the flame of candle, around the wick.

Now sometimes, you see a dark cone into the flame of candle, around the wick. Where there’s no fire.

Actually, this is the place Where vaporised wax is coming off, from the candle, but hasn’t started to burn yet (or the place where Pyrolysis process is begin).

But after that cone, The hydrocarbons and oxygen in the air reacts from each other throughout the flame and their atoms begin to rearrange.

Now, How Light Actually Come From?

electrons jump int excited state

Sometimes electrons of those atoms jump into an excited state, and when they come back down again, they emits light. And, because all of the hydrocarbons converted into CO2, the bottom of the flame glows blue.

leftover carbon form tiny particles of soot.

But, not all the carbon from the candle gets converted into CO2, so leftover carbon atoms come together, and form tiny particles of soot. 

Which is heated up, and glow orange and yellow. Like the hot coals under a grill. 

This soot is glowing, where most of a candle’s light comes from (the yellowish-orangish part of a flame).

At the tip only carbon dioxide and water left

And, at the tip of the flame, all the soot has burned away, and we've only carbon dioxide and water left, floating off into the air. 

The Most Interesting Part?

Actually, You can investigate all the different parts of a flame ourselves, with just a cold piece of metal.

you've seen water vapour above the flame

When you put the metal at above the tip of the flame, you've seen water vapour. 

In the yellow part, you'll find carbon

And In the yellow part of the flame, you'll find soot or carbon which didn't burn. 

just above to the wick, you've found unburned wax

And down, just above to the wick, we can even recover unburned wax.

So, Flames look really cool. They’re almost hypnotic.

Why The Shape Of Flame Is That, What Is It?

Gravity pulls cool air down, and hot air rise.

Actually, Gravity pulls cool or dense air down, and makes the hot air rise, and this buoyancy is what gives flames their familiar shape. 

But What If You Light A Flame In Zero-Gravity?

If you light a flame in zero-g, (in the space station), it will look very different.

Fire in space station

Because there is no gravity in the space, All the molecules dispersed in all the directions. And the flame shape is almost rounded.

And also, because all of the chemical and quantum reactions. That makes a flame glow, can only happen where it meets the air. 

So even though flames look like solid cones, they are actually hollow.

What Actually Produce Heat When Fire's Burn Up?

It’s not the molecular ripping apart, that makes a flame hot. Actually the formation of new molecules and new bonds, creates heat. 

And this heat drives the chain reaction forward, vaporising the more fuel, slamming more molecules into one another, and making the fire burn on.

Our species has been gathering around fire for thousands of years, and sitting around, asking questions and telling stories over a flickering flame, is what helped made us human in the first place.

Stay curious Stay safe.

And if today's you learn something and know different facts about fire.

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