Is It Safe To Heat Hydrogen Peroxide?

Hydrogen Peroxide Heating

Table of Contents

When it comes to utility, hydrogen peroxide is the talk of the town. It is one of those chemicals that are extremely handy when it comes to household procedures. More than that, it is also used by industries to manufacture and purify goods.

The agent which is responsible for most of hydrogen peroxide’s tasks is the loose oxygen bound to its atom. As it is loose, it is susceptible to external stimuli and temperatures.

So it makes one wonder, can we increase hydrogen peroxide’s effect by heating it? Or is it safe to heat this chemical?

We will be answering all those questions and a lot more in this article. So without further ado, let’s begin!

Hydrogen Peroxide – What Is It Made Of?

Hydrogen peroxide is one of the most simple yet effective disinfecting agents we have in the market. The simplistic nature of hydrogen peroxide makes it so unique and the eliminator of a wide range of pathogens and microbes.

If you look at the chemical composition of hydrogen peroxide, it resembles water. Some might even call it water with high reactivity. As water is one of the most famous chemical compositions, something we see daily, it is not hard to memorize hydrogen peroxide’s composition as well.

The word “peroxide” is a tell-away itself. There is a hydrogen “per-every oxide” in the chemical. This means there are two hydrogen atoms as well as two oxygen ones to form this potent oxidizing agent.

However, unlike water, hydrogen peroxide is fragile, and the atoms in its structure are not tightly bound.

This property of hydrogen peroxide is responsible for its high reactivity and is the mechanism that drives most of its reactions. More of this fragile nature of hydrogen peroxide is discussed below!

The Loose Oxygen Atom

So far, we have discussed the chemical composition of hydrogen peroxide and its chemical resemblance to water. Now we can take a deeper look into how the atoms present inside this molecular are bounded together and their manifestations.

The oxygen and hydrogen atoms present in the peroxide molecule are linked via a covalent bond. Just like in water, one electron from hydrogen and one from oxygen join together to complete the valence shell configuration of both atoms.

But after the central oxygen is linked with two hydrogen molecules and has completed its octet, two lone pairs of electrons are present in the valence shell. These electrons are responsible for the adherence of another oxygen atom.

The additional oxygen atom comes close to the central oxygen and establishes something called a dative bond (also known as a coordinate covalent bond).

In this type of bond, the two electrons shared between the linked atoms are from a single side (the donor atom). In comparison, the other one accepts the two electrons (the acceptor atom) and completes its valence shell configuration.

By doing this, another oxygen atom binds with the central oxygen of the hydrogen-oxygen association and forms what is called hydrogen peroxide.

As the acceptor oxygen atom complies with the laws of chemistry and has a complete octet after binding with the donor oxygen atom, the bond establishes.

However, the dative bond is relatively weak and subjected to external stimuli compared to the regular covalent bond. It is very sensitive to conditions like sunlight and heat, and therefore responsible for the fragility of hydrogen peroxide atoms.

We will see how hydrogen peroxide responds to physical stress by the environment and if it is safe to heat hydrogen peroxide.

Effects of External Conditions On Hydrogen Peroxide

We have gone over some of the fundamental properties of hydrogen peroxide and how they work at the atomic level. Now to understand the mechanism behind the dative bonds and covalent bonds present in the hydrogen peroxide molecule, we have to look at the chemical as a whole.

Below are some of the most common conditions that hydrogen peroxide faces, along with how it responds to those stimuli. Though, one can expect hydrogen peroxide to break down in almost all of the usual environmental conditions we face on a day-to-day basis.

Some of them are:

In Air

Hydrogen peroxide is highly susceptible to reactions with air. It is one of the primary reasons why the hydrogen peroxide bottles people have at their homes aren’t effective, and they end up complaining about the lack of functionality of the chemical itself.

Unlike what some people might think, the air is not a single molecular structure. Rather, it is a homogenous mixture of different gasses and particles forming the media surrounding us.

The majority of air we breathe is composed of nitrogen, oxygen, argon, carbon dioxide, water vapors, and other gasses in trace amounts.

So how do these gasses interact with hydrogen peroxide? The oxygen atoms present inside the air constantly replace and react with the acceptor oxygen atom present inside the hydrogen peroxide molecule.

This makes the dissociation process speed up, and it doesn’t take long when all of the hydrogen peroxides react with the surrounding air to liberate water vapors and oxygen gas.

In Heat

The most notable is the effect of heat on the chemical. We have hinted at the process in the above-mentioned sections, but in this segment, we’ll have a deeper look into what goes on in the chemical once the surrounding temperature is raised.

In any chemical process, regardless of its origin, heat speeds up the process of a reaction. The primary way this happens is when we increase the temperature, we increase the energy (particularly kinetic energy) of the molecules present.

This, in turn, causes them to move vigorously and shake, enabling them to break off from the parent atom easily and move away (to stabilize all of this excess energy).

Similarly, whenever heat is increased around hydrogen peroxide, the atoms present inside the molecule start to gain kinetic energy and want to break off from the structure. All in all, this results in hydrogen peroxide breaking down faster into water and oxygen molecules.

Under Light

Now that we have gone over the two processes that can speed up the breaking down of hydrogen peroxide, the final (and the one most people forget) is the effect of light, more particularly the sunlight, on hydrogen peroxide.

By now, you must have a general idea of what goes on in the molecular structure of hydrogen peroxide. And one can guess how sunlight is the primary source of light and heat in the world (emphasis on heat). Not only that, but sunlight contains radiation of all kinds.

Although most of them are blocked at Earth’s ozone layer, some escape, the most notable is the harmful UV rays that cosmetic companies talk about.

UV rays are high-energy radiation waves that are responsible for damage to skin cells, as well as countless other environmental processes that are too minute to be noticed by bare eyes.

For instance, they are responsible for generating chloroform gas from chlorine molecules in the presence of methane gas. This shows how UV rays are strong enough to break covalent bonds (and, of course, dative bonds stand no chance!)

Hence, whenever such a UV-ray particle strikes a hydrogen peroxide atom, the dative bond is broken. This catalyzes hydrogen peroxide breakdown reaction into water and oxygen molecules.

We can use this process to increase the effectiveness of hydrogen peroxide under calculated conditions (as in promoting iron rust using hydrogen peroxide). However, generally, sunlights are responsible for constantly wasting away the hydrogen peroxide chemical present inside bottles.

What Happens When You Heat Hydrogen Peroxide

Now that we have gone over some of the effects of the external environment on our disinfecting agent, it’s time to address the main topic of discussion: what is the response of hydrogen peroxide against heat?

Some of the essential points are already highlighted in the previous sections. However, we should always keep hydrogen peroxide. We will talk exclusively about what goes inside the molecule structure of hydrogen peroxide when heated.

Decomposition Process

If we were to summarize all of the effects of heating on hydrogen peroxide, it would decrease stability. Now, this does not precisely explain the “safety” of the process of heating hydrogen peroxide, rather just the chemical part of the reaction.

Hydrogen peroxide maintains its shape quite well under a cool, dark place. But once it’s subjected to heat and light, the atoms inside the molecule begin to gain energy.

There is a direct relationship between heat, energy, and the temperature of a media. And the basic concept dictates that once an atom gains energy, it loses stability.

Therefore, heating is a process in which hydrogen peroxide becomes unstable and breaks down.

Simply, hydrogen peroxide breaks down and releases oxygen and water. The boiling point of hydrogen peroxide, i.e., the point at which hydrogen peroxide liquid starts to turn into gas, is at about 150 degrees Celsius.

Before this, all of the gas that hydrogen peroxide liberates is oxygen, and the leftover liquid is water.

Heating a hydrogen peroxide mixture (diluted) is another process. At about 100 degrees celsius, though hydrogen peroxide is being broken down and turned into water, the water present in the solution is rapidly being turned into vapors and liberated.

So, it results in a higher volume/volume ratio of hydrogen peroxide and, thus, an increased concentration.

Some Common Concentrations of Hydrogen Peroxide

Now that we have discussed what happens to hydrogen peroxide at boiling temperatures, we can move on to discuss some of the commonly available hydrogen peroxide concentrations. Moreover, we will also discuss what happens if they are heated!

≤ 3% Hydrogen Peroxide

3% hydrogen peroxide is one of the most common disinfecting agents in the market. It is widely used in households as well as hospitals for cleaning, disinfecting, bleaching and drying.

The most notable task of 3% hydrogen peroxide concentration (or lower) is to clean and irrigate wounds and eliminate pathogens present over the body.

At these concentrations, hydrogen peroxide is safe for being used in the form of mouthwashes and nasal sprays to prevent hundreds of infections.

Heating this concentration of hydrogen peroxide will cause it to break down faster. If heated for a while, most of the chemicals will turn into water and oxygen and thus, become ineffective.

However, if the heating is regulated and done at precise temperatures, hydrogen peroxide can be concentrated by selectively evaporating water.

And you should never heat hydrogen peroxide on a stove. It can lead to the accumulation of oxygen gas and turn into an explosion. More of what happens during this process is discussed in the subsequent sections.

10% Hydrogen Peroxide

The mid-range concentrations of hydrogen peroxide are somewhat less common than the 3% ones. However, they are primarily used in the fields of mining, leather tannery, water purification, and chemical manufacturing.

The effects of heating 10% hydrogen peroxide concentration are very similar to the 3%. However, you should not use this version of hydrogen peroxide inside your homes due to its potent effects on the skin and body.

≥ 35% Hydrogen Peroxide

At this concentration, hydrogen peroxide is powerful and not available in standard drug stores. These high chemical concentrations are primarily used for explosives, rocket fuel, and food manufacturing.

As the concentration of hydrogen peroxide gets purer, it becomes safer for heating. However, at this concentration, they are not safe themselves, so it negates this effect. The purer forms of hydrogen peroxide lack water vapors and therefore retain their composition before turning into water and oxygen.


Now that we have gone over some of the most common concentrations of hydrogen peroxide and how they respond to heat stress, we can discuss some of the burning questions people have regarding hydrogen peroxide and heating.

Can I Heat Hydrogen Peroxide On A Stove?

The answer to that question is a resounding NO! Here we should rephrase the question: Why would you want to heat hydrogen peroxide on a stove?

Don’t get us wrong, hydrogen peroxide is somewhat safe for heating and doesn’t respond violently if it’s heated. However, the thing with heating hydrogen peroxide is it makes it lose stability and release oxygen and water atoms. And if you haven’t realized yet, oxygen is a highly explosive chemical, and right now, it is placed over a literal fire!

The results of heating hydrogen peroxide on a stove can be detrimental if it is mishandled. So make sure you are not making that mistake at home, and keep hydrogen peroxide away from fire.

Can I Microwave Hydrogen Peroxide?

The question of whether or not you can microwave hydrogen peroxide is not a one-worded answer. Because you see, hydrogen peroxide has a higher boiling point than water, and yes, it is theoretically “safe” to heat hydrogen peroxide.

But most of the hydrogen peroxide you and I buy straight from the market has up to 96% water!

On the other hand, water has a lower boiling point than hydrogen peroxide and, therefore, can escape in the form of vapors. And if it’s heated for a while, rapid build-up vapor may increase the pressure inside the microwave compartment and damage the machine.

So long story short, yes, it is safe to heat hydrogen peroxide in the microwave, but you should be careful while doing so as it is not the most ideal of procedures.

Should I Keep Hydrogen Peroxide Under The Sun?

As mentioned under the subsection of effects of light on hydrogen peroxide, sunlight increases the breakdown of hydrogen peroxide into water and oxygen gas. So the real question is, what is the goal behind keeping hydrogen peroxide under the sun?

For storage purposes, hydrogen peroxide should always be kept AWAY from the sun. The ideal spot is cool, dark, and away from direct air. The normal lifespan of hydrogen peroxide in a stored bottle is about 3 years.

However, due to improper storing techniques, this can decrease significantly to mere months or weeks.

If keeping hydrogen peroxide is a part of a procedure that aims to increase the oxidative effects of the chemical, then yes. By allowing direct sunlight over the hydrogen peroxide, you can increase its breakdown rate and, in turn, the number of oxygen atoms it liberates per unit of time.

Which Concentration Of Hydrogen Peroxide Is Most Resistant to Heat?

This is a tricky question, you see. Usually, the safest and best-suited concentration of hydrogen peroxide is the lower one, particularly the 3% hydrogen peroxide concentration. However, that is not the case when it comes to heating the chemical.

The hydrogen peroxide which is most resistant to heat is the one that is pure and without any stabilizers (as seen in diluted concentrations).

Concentrations like 96-99% hydrogen peroxide are perfectly safe for heating up to 150 degrees Celsius, beyond which they start to decompose. However, in a standard household setting, this concentration of hydrogen peroxide is certainly not safe!

The 3% hydrogen peroxide concentration does not respond well to heating on the other end of the spectrum. For once, by heating, the water vapors escape leaving a higher concentrated version of the product.

Secondly, due to the decreased stability during heating, the 3% hydrogen peroxide concentration becomes inactive if it’s heated for a particular amount of time.

Some Safety Precautions

Now that we have completely made ourselves aware of what happens in a hydrogen peroxide reaction and some of the effects of foreign stimuli on the chemical, we can discuss some of the safety precautions you must take around it, especially during heating.

The foremost safety tip is to make sure you have protective gear on when handling higher concentrations of hydrogen peroxide for more extended periods. Normally the 3% hydrogen peroxide concentration seldom causes any adverse side effects or reactions over the skin.

However, if your procedure involves using the said chemical for more extended periods, say 15 to 20 minutes, you should watch out for rashes and itchy spots that appear due to skin damage by hydrogen peroxide. One way is to wash your hands with water regularly.

The better alternative is to use gloves and goggles while performing the procedure for absolute safety and precaution.

The next tip should be common sense, which keeps hydrogen peroxide away from the eyes, mouth, and nose.

Though the effects of hydrogen peroxide are not so evident on the skin because multiple layers of anucleated cells protect it, the eyes and nose are highly sensitive to hydrogen peroxide.

Not only are the eyes and nose have a single or dual layer of cells, but the neuron receptors also lie very close to the surface of these organs. Therefore, small concentrations of hydrogen peroxide are enough to cause eruptive damage and pain during exposure.

One Final Tip!

The final and most relevant safety tip to our current article is to make sure you are storing hydrogen peroxide adequately.

As we have discussed throughout the article, the chemical is sensitive to light and heat. And the lifespan of a hydrogen peroxide bottle decreases drastically once it has been exposed to air or an external environment.

Therefore, before beginning a procedure, make sure the hydrogen peroxide you are using is not expired. One way you can do this is by pouring some of the hydrogen peroxides down the kitchen sink and looking for any bubbling or sizzling sounds.

If the hydrogen peroxide is active, it will react with the organic matter present inside the sink and release oxygen in the form of bubbles. This will express in the form of sounds and verify that hydrogen peroxide is okay to use.

The Takeaway

Hydrogen peroxide is one of the most valuable chemicals we have on the market. Its oxidative properties are second to none. And the same oxidative properties are used in countless reactions and procedures that involve household as well as industrial settings.

However, the same reactivity of hydrogen peroxide makes it sensitive to heat and temperature changes. Heating hydrogen peroxide decreases its stability and encourages water and oxygen formation.

So if you are someone who loves DIY procedures, hydrogen peroxide is the perfect tool for you. So order your set of hydrogen peroxide bottles today, and make sure to store them in a cool, dark place!

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Faizan Khan
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