If you did any chemistry at all in school, then you probably remember an experiment with sodium. Typically, it’s conducted behind a big see-through plastic shield, and everyone has to wear goggles too. Then the teacher drops some sodium in water, it catches fire and then whizzes about for a bit and if things go wrong, it explodes and breaks the container, but does this mean that sodium is flammable?
Sodium is a highly reactive metal that is flammable. It can ignite with a spark at 239 degrees Fahrenheit or 115 degrees Celsius. It can also catch fire without a spark when it reacts with certain substances, such as water.
Sodium is not the same as table salt, as we will go into more detail about below. This metal can be dangerous in certain situations, so let’s take a closer look at sodium and how it behaves with fire.
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Also read: What Makes Something Flammable?
Sodium, which has a chemical symbol of Na (derived from the Latin word natrium), is a very soft metal famous for its incredible level of reactivity.
In fact, sodium is so reactive that the metal doesn’t occur by itself anywhere in nature, because as soon as it came into being, it would have reacted with things around it to form compounds.
However, sodium is still the sixth most common element in the earth’s crust and it can be found in a wide range of minerals including salt (NaCl) which is the stuff that most people use to season their food with.
Also read: Is Calcium Flammable?
Is Sodium Flammable?
Sodium burns in the air and has a typical ignition point of 115 degrees Celsius or 239 degrees Fahrenheit.
This means that sodium is relatively flammable and can catch fire at moderate temperatures. Care should be used with sodium and fire.
Though the correct term for sodium is “combustible” from a chemistry point of view, which is a solid that catches fire easily.
However, this is not the whole story when it comes to sodium and you can, in fact, trigger a chemical reaction that leads to fire at much lower temperatures with pure sodium.
Also read: Is Lead Flammable? Will it Burn?
Sodium Reacts with Water
In our school chemistry lessons, our teachers did not take a match to sodium to get it to burn.
Instead, they threw it in some water.
Sodium reacts violently with water in an exothermic reaction which releases a lot of heat (as fire).
It produces Sodium Hydroxide (NaOH) and Hydrogen gas (H2) this is a problem because hydrogen is also flammable, very flammable. And if you put enough sodium in the water, it will release large amounts of hydrogen, which could burn down a building.
Take a look:
Also read: Is Sulfur Flammable?
Why Is Sodium Usually Stored In A Jar Of Oil?
This is why schools don’t keep that much sodium on hand and the sodium that they do keep, tends to be submerged in oil (to keep water and oxygen out) and it’s only brought out to slice tiny pieces off to throw in water to show a class of eager students the consequences of doing so.
Sodium can catch fire without an ignition source when mixed with water.
Also read: Is Iodine Flammable?
What Happens If You Hold Sodium In Your Hand?
It is this reaction that also means that should you ever have to handle sodium; you need to wear gloves while doing so.
Your hands sweat and sweat contains water, enough water to react with the sodium and set fire to it, and thus, because you’re holding the sodium, it burns your hands.
It is also worth noting that sodium hydroxide is a caustic substance and if you breathe in fumes of it, it can damage your lungs.
So, stand well back before you drop the sodium into the water too.
Also read: Is Potassium Flammable? Violent Reactivity
Extinguishing A Sodium Fire Is Challenging
It is also worth noting that sodium fires are very problematic to extinguish.
You can’t use a water extinguisher because sodium reacts with water to create more flames, hydrogen and sodium hydroxide, which is what you’re trying to prevent.
You can use a carbon dioxide extinguisher either because this leads to sodium reacting with the CO2 to form sodium carbonate and more flames.
So, you’ll need a Class D powder extinguisher or something similar to put out a sodium fire.
Also read: Does Metal Burn In A Fire? Examined
What Color Is A Sodium Flame?
If your sodium catches fire, it should burn with a yellow flame, and this is a simple test to see if sodium is present in compounds for qualitative chemists.
Sodium ions also give off the same color flame.
Does Sodium Melt?
Assuming that you keep sodium out of the air, water and other substances that it can react with (and that is most substances) you can get sodium to melt.
It forms a liquid at 97.82 degrees Celsius or 208.1 degrees Fahrenheit.
If you intend to melt sodium, you need to ensure that there is enough oil in the container to completely covered the molten sodium or it is entirely possible that the moisture in the air will be enough to ignite it.
Also read: Burning vs. Melting: What’s The Difference?
Does Sodium Boil?
Sodium can also be boiled, assuming that you can heat it for long enough under an oil which doesn’t boil off before the sodium boils.
The boiling point of sodium is 881.4 degrees Celsius and 1,618 degrees Fahrenheit.
It is very important to realize that boiling sodium in a standard laboratory would be dangerous. Sodium vapor that escaped into the air would ignite immediately due to the moisture present and that would, almost certainly, propagate throughout all the sodium gas causing an explosion.
Why Don’t Sodium Salts Burn Very Well?
Salt, NaCl, is the most common sodium salt and if you’ve read our piece on whether salt is flammable, you’ll know that it’s not.
So, why is it that sodium can catch fire so easily, but you can use salt to put out fires?
Well, it’s because sodium is very, very reactive.
So, once it bonds to another substance in a chemical reaction (in the case of salt the other substance is chlorine which is also very reactive) it forms a very strong bond with it.
If you want to burn the sodium salt, you first need to break this bond and that requires a huge amount of energy.
It’s not impossible to heat NaCl so much that the bonds between sodium and chlorine break, but it does require huge amounts of energy and more energy than you would generate in a house or office fire.
Is Sodium Poisonous?
Sodium, in small quantities, is essential for human life (and, indeed, all animal life).
As you know NaCl is table salt and most of us cook with it on a regular basis.
We’d hardly do that if we were poisoning ourselves with each meal.
However, large quantities of sodium can be problematic for us and other sodium salts may have harmful effects beyond that of salt or sodium metal.
For example, sodium hydroxide is caustic because it is extremely alkaline.
If someone were to breathe in high volumes of fumes containing sodium or to eat too much sodium (for example, by consuming a 1 Kg bag of salt) this can have very negative consequences.
Firstly, high levels of sodium cause dehydration (which is one of the reasons we can’t drink sea water, the other is that it will make us vomit) and oddly, dehydration can cause high levels of sodium too.
Too much sodium in the body means that our cells dispel water to try and dilute it and that harms the cells and in the case of brain cells, it absolutely destroys them.
If the process goes on for very long, you can end up with water trapped in your lungs, preventing you from breathing, damage to your kidneys, and eventually it can lead to death.
So, no sodium is not poisonous in ordinary circumstances, but it can become poisonous in specific circumstances when you ingest or inhale far too much of it.