Hydrogen peroxide (H 2 O 2 ) is a substance that is freely available in a pharmacy. The peroxide that we buy is a 3% solution: that is, the bottle with the substance is 97% water. Hydrogen peroxide in this solution accounts for only 3%.
Most people use this substance as an antiseptic. Although few know that peroxide is not effective enough as an antiseptic. Nevertheless, it does not harm, getting on cuts and scratches, moreover, when it comes into contact with a wound, peroxide forms a spectacular “show”. So why does hydrogen peroxide foam on a wound? What is the scientific explanation for this impressive phenomenon? Find out in the article.
Why does hydrogen peroxide foam on a wound?
The reason foaming occurs is because the blood cells and the blood itself contain an enzyme called catalase. Since a cut or scratch is always accompanied by blood secretion and damaged cells, a lot of catalase always forms around the wound. They understood this, but still, why does hydrogen peroxide foam on the wound? When catalase comes in contact with it, it converts hydrogen peroxide (H 2 O 2 ) into water (H 2 O) and oxygen (O 2 ).
Catalase carries out the process of splitting peroxide into water and oxygen extremely efficiently - up to 200,000 reactions per second. The bubbles that we see if hydrogen peroxide foams on the wound are oxygen bubbles formed as a result of the action of catalase.
Entertaining chemistry
If you try to recall school chemistry lessons, then images will certainly arise in the head: in the classroom, a teacher pours a small amount of hydrogen peroxide onto a potato slice - the same thing happens. The teacher asks: “Why does hydrogen peroxide foam on the skin you hurt and on the potatoes?” Without waiting for an answer, the teacher himself replies: "Because catalase is released in damaged potato cells, like damaged epidermal cells."
Peroxide does not release foam in a bottle or on whole skin, because they do not have catalase, which causes a reaction. Hydrogen peroxide is stable at room temperature.
Have you ever wondered why hydrogen peroxide bubbles appear on a cut or wound, but it does not bubble on intact skin?
Why hydrogen peroxide foams and hisses: a scientific explanation
So, we found out that hydrogen peroxide turns into bubbles when it comes in contact with an enzyme called catalase. Most cells in the body contain it, so when the tissue is damaged, the enzyme is released and becomes available for reaction with peroxide.
Catalase allows decomposition of H 2 O 2 into water (H 2 O) and oxygen (O 2 ). Like other enzymes, it is not used in the reaction, but is recycled to catalyze more reactions. Catalase supports up to 200,000 reactions per second.
The bubbles that we observe pouring an antiseptic into a cut are bubbles of gaseous oxygen. Blood, cells, and some bacteria (such as staphylococci) contain catalase. While on the surface of the skin it is not contained. Thus, peroxide, in contact with intact skin, does not react, and bubbles do not form.
In addition, since hydrogen peroxide has such a high level of activity, this substance has a certain shelf life after opening. In other words, if the release of bubbles during the application of hydrogen peroxide on a wound or blood section is not observed, it is likely that the peroxide is no longer active, and its shelf life has long expired.
Hydrogen peroxide as an antiseptic
The earliest use of hydrogen peroxide was as a bleach, since oxidation processes have a good effect on the change or destruction of pigmented molecules. However, since the 1920s, peroxide has been used as a powerful disinfectant. Therefore, the question: “From what does hydrogen peroxide foam on a wound?” - People have been asking for more than a century.
The healing properties of peroxide
The chemical characteristics of peroxide are ensured by the fact that it is able to treat wounds in several ways. Firstly, since it is an aqueous solution, peroxide helps wash away dirt and damaged cells and “loosen” the crust of dried blood. Bubbles in this case help remove debris from damage.
Although it is worth noting that the oxygen released by peroxide does not destroy all types of bacteria. In addition, peroxide has strong bacteriostatic properties, which means that the use of hydrogen peroxide on a wound helps prevent the growth and reproduction of bacteria. Peroxide acts as a sporicide, killing potentially infectious fungal spores.
However, it is not an ideal disinfectant, since it also destroys fibroblasts. This is the type of connective tissue that body cells use to quickly heal wounds and repair damaged areas of the skin.
Thus, peroxide should not be used as an antiseptic on an ongoing basis in the treatment of wounds, since it can slow the healing process. So, most doctors and dermatologists advise not to use it to disinfect open wounds, because this only exacerbates the situation.
Check: is peroxide active in the vial?
In the end, hydrogen peroxide consists of water and oxygen, that is, using peroxide on the wound, you mainly use ordinary water. Fortunately, there is a simple test to make sure that the vial of hydrogen peroxide contains the active substance: just pour a small amount of liquid into the sink. Metals (for example, near drainage) catalyze the conversion of peroxide to oxygen and water - that is why hydrogen peroxide foams on the wound and even on the sink!
If bubbles form, you can be sure: peroxide is effective. If you don’t see them, it's time to go to the pharmacy for a new bottle of hydrogen peroxide. It is worth recalling that storing the medicine in the right conditions helps to extend the shelf life. Make sure it is in a dark container and in a cool place.