When hydrogen peroxide comes into contact with an open wound, it causes a chemical reaction that breaks down the hydrogen peroxide into water and oxygen. The oxygen produced in this reaction forms bubbles that fizz on the surface of the wound. This bubbling action helps to clean the wound and remove any debris or bacteria, which can help to prevent infection.

The bubbling reaction also helps to stop the bleeding from the wound. When the hydrogen peroxide breaks down into water and oxygen, the oxygen helps to form a scab over the wound. This scab helps to seal the wound and prevent further bleeding.

In addition, the hydrogen peroxide helps to kill any bacteria that may be present in the wound. The oxygen produced by the reaction is toxic to bacteria, so it helps to kill off any bacteria that may have entered the wound. This can help to prevent infection.

Overall, the bubbling reaction of hydrogen peroxide when applied to a cut helps to clean the wound, stop the bleeding, and kill any bacteria that may be present. This helps to prevent infection and promote healing.