Does Hydrogen Peroxide Evaporate | Explained

Does hydrogen peroxide evaporate when exposed to air? How long it take to get spoiled, and what causes this evaporation + spoilage? This article explains the deterioration of hydrogen peroxide.

Introduction:

Before we explain the topic "does hydrogen peroxide evaporate?” it is quite important to first understand its basics. Hydrogen Peroxide or H₂O₂ is a colorless liquid when in its pure form and is commonly found in a 3% concentration used in commercial products for household purposes. You might misjudge it with water in appearance, but it is slightly more viscous. It has a high boiling point and is completely miscible with water. It is used as an effective disinfectant and bleaching agent.

Its molecules have a bent or V shape where there is an O-O bond where each oxygen atom is bonded to a hydrogen atom. This molecule’s structure is quite similar to a water molecule but with an extra oxygen atom bonding (peroxide bond), creating an oxygen-oxygen bond. This extra bond is quite unstable and makes it decompose especially when it is exposed to light or heat. This causes it to evaporate when exposed to air.

Why does Hydrogen Peroxide Evaporate?

As explained above, hydrogen peroxide has one extra bond in its molecular structure which makes it quite unstable. That contributes to the following three reasons why hydrogen peroxide evaporates:

1. It has a low vapor pressure, making it evaporate when left open for longer periods. But it should be kept in mind that it has a lower vapor pressure as compared to other liquids for example water. This makes it evaporate more slowly under standard conditions. This lower vapor pressure is due to hydrogen peroxide’s higher molecular weight and intermolecular forces which include hydrogen bonding.

2.It decomposes when exposed to open air, light, or heat. This also causes its evaporation in water and oxygen as shown in the reaction below:

2H₂O₂  →  2H₂O + O₂

3. High temperatures and light can also accelerate its decomposition (evaporation), which is why it is typically stored in opaque or dark-colored bottles to minimize exposure to light. If left exposed to air, you may notice a loss of clarity in its color. This cloudiness can indicate its decomposition, though it isn’t always visibly detectable. If it takes the color of the dark or yellowing liquid, then it suggests that significant degradation has already taken place, and such hydrogen peroxide should not be used for disinfection purposes. 

Even if contained in properly sealed containers, hydrogen peroxide can decompose within the container if exposed to light. In this case, decomposition leads to a reduction in hydrogen peroxide concentration, making it less effective as a disinfectant or bleaching agent. This decomposition causes the release of oxygen in the containers, which is what causes the fizzing effect when hydrogen peroxide is applied to a wound or mixed with certain substances.

Expiry of Hydrogen Peroxide:

Even in ideal storage conditons, this chemical can slowly decompose and evaporate within the container and can be slowed down by keeping it in the dark and sealed containers placed in a cool place. Most commercially available hydrogen peroxide you will find, e.g., 3% solutions come with an expiry date of about 1 to 3 years if stored properly in a cool, dark place.  This reduces once the lid is open and will depend on the quality of storage conditions.

Hydrogen peroxide is a very common disinfectant and bleaching agent and is of great importance to global business for various purposes. One of the common issues in importing it is with properly managed storage conditions and purity thresholds. At Echemi, such chemicals are provided by certified and reputed suppliers, who are checked and evaluated to maintain proper storage conditions before and after shipping so that you get the purest and highest quality possible.

Conclusion:

We explained above why does hydrogen peroxide evaporates and how to avoid its evaporation and decomposition. Having said that, it always comes with an expiry date, and after that date, one should avoid using it. To keep hydrogen, peroxide effective when within its expiry date, store it in a cool, dark place in its original opaque container and keep it sealed when not in use.