Final answer:
When hydrogen peroxide decomposes, it results in the formation of bubbles due to the release of oxygen gas. This effervescence is the direct observable outcome, different from color change indicators used in certain titration methods.
Step-by-step explanation:
For hydrogen peroxide, the visibly seen indication of the endpoint during its reaction is the formation of bubbles. When hydrogen peroxide is introduced to a substance such as manganese dioxide, it decomposes into water (H₂O) and oxygen gas (O₂). This decomposition is a chemical change where the original bonds between hydrogen and oxygen in hydrogen peroxide are broken, and new bonds form to create water and oxygen gas.
The presence of oxygen gas can be confirmed by the effervescence, which is the rapid formation of bubbles that you can observe. For instance, in the catalase test, the production of bubbles upon the addition of hydrogen peroxide indicates the presence of the enzyme catalase. In tests where a visual endpoint is required, such as titrations, a color change might be seen when an indicator is used, but this is not related to the intrinsic properties of hydrogen peroxide.