Is Iron Flammable?

This article will answer the following question: “Is Iron Flammable?”. We will understand what it would take to burn iron or not, and other important iron properties.

Is Iron Flammable?

More or less. Pure iron can burn under some conditions, but only in the form of wool or something that has a high surface area. But even so, the burning of iron is very different from a usual fire.

What is Iron?

Iron is a chemical element. It’s more commonly found in the forms of alloys in the Earth’s crust, where it’s harvested to compose metal materials for us.

Pure forms of iron can’t really be found naturally, not originally. Although iron is common in meteorites, so we can find pure forms of iron that “naturally” came from extraterrestrial sources.

Iron has the ability to form many kinds of ores. Its chemistry is wide.

Iron chemistry

To understand how flammable iron is, we first need to state a few important chemistry stuff.

Iron is a chemical element. It barely exists naturally on our planet, in its pure form. In the Earth’s crust, it can be found as magnetite and hematite, in the form of oxides.

The iron we use commercially was extracted from these alloys.

The most common form of iron we can find in our day-to-day is steel, which is a form of ore made with carbon.

Like many kinds of metals, iron can form really durable, strong, and cohesive materials, through a chemical interaction known as an alloy.

Like most metal ores, iron has a high thermal conductivity.

Here’s a few iron properties:

  • Phase at STP: solid
  • Melting point: 1538 °C, ​2800 °F
  • Boiling point: 2862 °C, ​5182 °F
  • Density: 7.874 g/cm3
  • when liquid: 6.98 g/cm3
  • Heat of fusion: 13.81 kJ/mol
  • Heat of vaporization: 340 kJ/mol
  • Thermal conductivity 80.4 W/(m⋅K)
  • Molar heat capacity: 25.10 J/(mol·K)
  • Oxidation states : −4, −2, −1, 0, +1, +2, +3, +4, +5,+6, +7

Where did iron came from?

The iron in our blood cells, in our car’s chassis, homes, planes, cutlery, and every other product came from Earth’s crust. 

It was assimilated by plants and passed through the food chain until reached our bodies.

What about before that? How had it reached Earth’s crust?

Most atoms were forged inside the core of stars. There are many kinds of stars in the universe, some of them are big enough to craft heavy atoms after the stars die.

Stars die when they run out of fuel, normally hydrogen. This combustible, although, is not burned with flames how we are used to, it’s consumed during nuclear fusion.

There are two major forces constantly acting upon a star: gravity and something called “strong force”. This last one is the interaction that glues atom nuclei and make them concise.

Since stars have a lot of mass, their gravity is strong as well. But strong force prevents stars from shrinking more than they already are. 

But after this force lost power, gravity won. Can you imagine what happens next?

A star collapses and literally falls into itself. Nothing holds a star’s volume anymore, so it gets so dense that forces its particles to fuse. If the star is big enough, it produces bigger atoms.

This way iron is produced and unleashed out there in the Universe. 

Therefore, iron is much older than our own planet.

These atoms eventually amalgamated enough so they acquired gravity again, and eventually formatted our planet.

Is Iron flammable?

It depends on the product. Iron is only considered flammable in its powder or wool form, or any other shape in which the surface area is high. 

A piece of iron is not capable of releasing energy if flames, intense heat, or sparks are added to it. It just won’t burn.

In fact, Iron can oxidize but not in the same way we’re used to seeing in fuels. Fire is a complex chemical reaction as we will see, and it doesn’t happen with inorganic compounds.

At the same time, rust is the result of Iron oxidation. It is a chemical reaction that generates heat like when we burn iron, but it takes a lot of time to happen, and the heat gets dispersed easily.

But it doesn’t mean that iron would not release energy if we apply flames to it or toss it into a fire. Let’s see how it’d happen.

How flammable iron wool is?

Well, to answer this question we need to compare iron with something else that can burn. Let’s say, alcohol. Overall, iron it’s not much flammable.

In order to make a fair comparison, we must imagine the same amount of iron and alcohol (ethanol burning). 

Steel wool is a very fluffy material, it’s not dense at all and feels very light if we grab it. We would need a lot of it to produce a lot of heat, unlike other common fuels that have a high combustible ratio.

A piece of fluffy iron wool that fits in the palm of your hand would weigh no more than 8 grams/0.28 ounces. We can apply a simple rule of three to understand how much energy this would generate.

Since each gram of iron liberates around 4,5kJ of energy in the form of heat, to form iron (II) oxide, that piece of wool we spoke about would generate 8 times this value, around 35 kJ.

It’s not important to understand what kiloJoule (kJ) means. We will just use it for comparison.

Now, how much alcohol liberates the same amount of energy?

So, alcohol liberates around 30kJ for each gram of the product.

But alcohol is a liquid, so we first need to understand what is the volume of 1g of it.

Alcohol’s density is 0.78945 g/cm3, which means that every milliliter of alcohol weighs 0.78945 grams. 

By applying another simple rule of three we will end up dividing weight over density (Volume=weigh/density), resulting in a small volume of 1,27ml/ 4,30 fl oz.

Ok so, we have 1g of iron resulting in 35kJ of heat.

We also have 1,27ml of alcohol resulting in almost 30kJ of heat.
This is because ethanol’s heat of combustion is around 30kJ/gram.

Since the values are similar, we can say that a piece of iron wool that has the size of your hand would burn as much as one-fourth (1/4) of an alcohol teaspoon.

By this comparison, we can say that, in normal conditions, iron wool is not very flammable, unless you have a lot of it. But is it a fire hazard?

Is iron a fire hazard?

Well, it depends. As we saw, iron is flammable if in a wool or powder form, even though no flames actually arise from it, but it’s not a big fire hazard.

It can become a fire hazard if direct flames are applied to it, if you possess a big amount of iron wool to be burned, for example.

Although a small piece of iron wool can liberates sparks all around if it’s litten, it can be the ignition for a bigger fire if it reaches another source of fuel. 

At the same time, iron must before be ignited itself so it can ignite other things, so it’s a small fire hazard.

What kind of iron is flammable?

In this section, we will discuss some specific iron products’ flammability. Overall, iron is only flammable when has a high surface area.

This product is intended to be used as Low carbon steel wool, hand pads, and reels. It doesn’t possess many hazards according to the manufacturer.

Although, it will “burn quickly when ignited”. 

The conditions to avoid for this product are moisture, heat, flames, ignition sources, and dusting. If it eventually burns, toxic iron oxides will be produced.

This kind of substance, although, has bigger particles. According to the manufacturer, it is not flammable.

It doesn’t mean that it would never burn, only that it wouldn’t burn under usual circumstances, which include industrial.

This material is not considered flammable. It is an ore made with Carbon, Chromium, Copper, Iron, Nickle, Silicon, and Tin.

It requires temperatures above 2300ºF to melt, burning would occur in temperatures even higher, which can’t be achieved normally.

Conclusion

Under the right conditions, iron can burn and is considered flammable because it can burn quickly. At the same time, such burning doesn’t liberate much energy and isn’t a problem on its own.

Any form of pure (or almost pure) iron would burn in a fire if its particles have a high surface area because the heat and oxygen gas can reach much easily each iron atom.

Frequently Asked Questions (FAQS): Is Iron Flammable?

is iron a mineral?

Iron is a mineral that can be found naturally in minerals like magnetite and hematite, for example. At the same, the iron atom is a metal that belongs to the first transition series in the periodic table.

is iron fire resistant?

Not particularly. A metal bar is not likely to catch fire, but iron wool or powder might if direct flames are applied to it.

Although, iron is normally found in ores, which normally alters the properties of the material quite a lot, making it much more resistant to melting and even more difficult to be burned.

It’s important to note that iron has a high thermal conductivity. Heat can travel easily through it. This means that it can take heat from one point to another, something not desired for fire-resistant materials.

Is iron magnetic?

Yes. Many kinds of metals are magnetic, and iron and its ores are the most common magnetic materials, capable of being attracted by a magnet.

Magnetism happens due to a specific property of the ore called magnetic dipole moment, which can be native to the material or forced by an electromagnetic field.

Citations

https://en.wikipedia.org/wiki/Iron
https://en.wikipedia.org/wiki/Type_Ia_supernova
https://en.wikipedia.org/wiki/Steel
https://en.wikipedia.org/wiki/Strong_interaction
https://imgcdn.mckesson.com/CumulusWeb/Click_and_learn/GMA117002_SDS.PDF
https://fluxana.com/images/CRM_data/FXMSDS_0169_01e_FLX_2001_iron_ore.pdf
https://www.tuftile.com/wp-content/uploads/2021/09/Cast-Iron-SDS.pdf

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