What is the oxidizing agent used in hair coloring that supplies oxygen gas?

The oxidizing agent used in hair coloring that supplies oxygen gas is hydrogen peroxide. In the hair coloring process, hydrogen peroxide plays a crucial role in both lightening the hair and facilitating the development of color. It releases oxygen, which interacts with the hair's melanin, leading to the decolorization process.

Hydrogen peroxide is effective for this purpose because it creates a chemical reaction that lightens the existing pigments in the hair shaft while simultaneously allowing color to deposit when used in conjunction with hair dyes. This oxidation process is essential for achieving the desired hair color and is a foundational principle in both permanent and demi-permanent hair color formulations.

The other options do not act as oxidizing agents in the same way. Ammonia, for instance, is used to open the hair cuticle, making it possible for the color to penetrate but does not supply oxygen gas itself. Alcohol is generally used as a solvent in cosmetic formulations and does not play a role in the oxidation needed for hair coloring. Water, while necessary for various chemical processes, does not function as an oxidizing agent in hair color application.