If you have left a bowl of water under the sun for a few hours, you might have experienced the effects of a process known as evaporation. It is the culprit behind a shallow bowl of water you might find after coming back, also the way how your body cools itself down.
Similarly, what happens if you leave the cap of the hydrogen peroxide bottle open for a few hours? Does the chemical evaporate as well, or is there another process at play?
Find out how evaporation actually occurs and what change hydrogen peroxide faces under light and air.
So without further ado, let’s begin!
The Evaporation Process
Before we can answer whether hydrogen peroxide can evaporate or not, we first have to understand what the evaporation process is and the mechanics behind it?
Evaporation is one of the most fundamental properties that molecules possess. To put it simply, it is the process where a liquid turns into a gas and liberates into the air. This can either be due to increased kinetic energy in the molecules or higher temperature of the surroundings (which in turn increases the kinetic energy of the molecules).
What happens is that the film of molecules that are present over the topmost surface of a liquid has higher energy than those present below them. The above molecules absorb the energy from the molecules present below. This way, they acquire enough energy to break off their liquid composition and turn into gas molecules.
And gases are lighter than liquid, so these molecules liberate or evaporate.
Evaporation v/s Boiling
Now that we know what evaporation is, we can address one of the most common misconceptions people have regarding this process.
Here is the thing, the temperature at which the liquid starts converting into gas is called the boiling point. However, evaporation is not dependent on the boiling point. But you may ask that evaporation is also the process of liquid converting into gas, just like boiling.
However, evaporation occurs at all temperatures. There is no set point for a film of liquid to start evaporating, just like there is not a point where the interconversion of energy will start or stop. Evaporation is a simple process of heat exchange where a few of the liquid molecules gain energy and liberate.
On the other hand, boiling involves reaching a certain temperature where the liquid under observation can begin converting into gas. You can say that at boiling point, evaporation of a liquid is maximum.
But how do these things affect hydrogen peroxide?
Hydrogen Peroxide – The Chemical
Now that we have looked into the process of evaporation and what exactly happens in it, the next part is to discuss the liquid under consideration, e.g., hydrogen peroxide.
Hydrogen peroxide or H2O2 is a chemical formed by bonding two hydrogens and two oxygen molecules. As it is quite similar to water, so are its physical properties. Hydrogen peroxide is liquid at room temperature. However, it has a higher boiling point than water and a lower melting one as well.
The key difference between hydrogen peroxide and water is the relative stability of both molecules. Water is a highly stable molecule formed by the covalent bonding of one oxygen atom with two hydrogens.
The species that form after the covalent bonding of hydrogen and oxygen has a lone pair of electrons in its valence shell. This pair of electrons is attracted by another oxygen atom which needs only two electrons to attain noble gas configuration (a fancy term for stable configuration).
So a bond is formed between the bonded and free oxygen. However, unlike the covalent bond, this bond is weak and easy to break. This property gives hydrogen peroxide its fragile nature and makes it a potent oxidizing agent (e.g., a molecule that liberates oxygen easily).
Misconception Behind Hydrogen Peroxide’s Evaporation
Here lies the heart of our discussion, what goes on whenever you spray hydrogen peroxide over a surface? Does it start evaporating like other liquids, or is there something else entirely that is responsible for the “sizzling” sounds you hear?
As it turns out, it is tough for hydrogen peroxide to evaporate.
Decomposing v/s Evaporation
Here is the thing, what happens when you keep a bottle of hydrogen peroxide open in the sun? Which process does the chemical go under? The answer to the question is hidden in the subsection above.
Hydrogen peroxide is a fragile chemical and does not last long in nature. When exposed to sunlight and wind, it starts breaking down into the water and liberates oxygen—the oxygen liberated from the chemical flow away.
The point you should note here is that the molecule which is breaking off from the liquid film is oxygen, not hydrogen peroxide itself. This fact makes things much more evident when it comes to the physical properties of hydrogen peroxide.
As hydrogen peroxide loses its chemical composition in normal circumstances, it becomes really hard for the actual molecules present above to acquire enough energy and turn into gas before breaking down.
Boiling Hydrogen Peroxide
Now that we have talked about the evaporation process and what goes into it, we can start to figure out what is the boiling point of hydrogen peroxide and what happens if the chemical reaches it?
Unlike water, the boiling point for hydrogen peroxide is higher than 100 degrees celsius. For the chemical to start boiling, you must heat it to 150 degrees. That too, without letting it break down.
What do you think happens when hydrogen peroxide reaches boiling point? Believe it or not, there is a vast difference between the hydrogen peroxide we have in our homes and the one used in industries. Pure hydrogen peroxide has 150 degrees boiling point. However, the hydrogen peroxide we have in our homes has 97% water.
This means, before reaching 150 degrees, hydrogen peroxide will become more and more concentrated, granted if you perform the procedure in an isolated environment to avoid decomposition of the chemical.
So theoretically, yes, it is possible to evaporate and boil hydrogen peroxide just like any other liquid. However, in real life, the conditions are a lot different, and the results are not proper.
Evaporation Process In Hydrogen Peroxide -The Implications
We have gone over all there is to know about the theoretical aspects of evaporation in general and hydrogen peroxide under the concept of evaporation.
Now it’s time to address the implications of the process!
Early Evaporation
When we refer to the term “evaporation”, we are talking about the one happening due to the decomposition of hydrogen peroxide, e.g., oxygen evaporation, not the evaporation of hydrogen peroxide itself.
As you might imagine, if hydrogen peroxide is kept outside in an open environment for a few hours, it will experience evaporation. However, unlike the evaporation of water, this will change the composition of the chemical as a whole, changing its properties and making it useless.
So evaporation in hydrogen peroxide due to the environment is not ideal and should be avoided. As a reference point, the closed bottle of hydrogen peroxide lasts for almost 3 years. However, once the bottle is opened, the expiration date narrows down to mere months. That’s how fragile hydrogen peroxide is in the air!
Checking If Your Hydrogen Peroxide is Good
In the above subheading, we have seen how evaporation in hydrogen peroxide can lead to the impairment of the chemical. But hydrogen peroxide and its reduced form (water) look almost identical. How can one differentiate one from the other before a procedure?
Well, we have got you covered on that as well! In order to check if your hydrogen peroxide is active or not, all you have to do is pour some of it down a kitchen sink. Yes, that’s right! It may seem somewhat ignorant at first, but it is a simple yet effective way to check for the reactivity of the chemical.
Kitchen sinks generally have enough organic matter present for hydrogen peroxide to immediately start reacting and give off its famous “bubbling” sounds.
If your chemical is expired or ineffective, such sounds would be very low or even absent.
The Bottom Line
Evaporation is a natural process that almost all liquids face. It is based on one of the most fundamental principles of heat transfer from one molecule to another.
Contrary to popular belief, evaporation and boiling points are not the same. Though, one factor might affect the other.
Hydrogen peroxide has a high boiling point when it comes to chemical properties. However, the chemical itself is very fragile and can dissociate quickly when it comes in contact with the open air.
The dissociation process of hydrogen peroxide releases gaseous oxygen. Therefore, it should not be confused with a similar process that involves the release of gaseous molecules from the parent liquid, e.g., evaporation.
The real evaporation process in hydrogen peroxide rarely occurs as the chemical dissociates before it can turn into liquid.
Apart from the bare essentials, there is so much more that you can do with hydrogen peroxide. So order your set of bottles today!
