* Light sensitivity: Hydrogen peroxide is sensitive to light, especially ultraviolet (UV) light. UV light acts as a catalyst, speeding up the decomposition process.

* Decomposition reaction: The decomposition of hydrogen peroxide is an exothermic reaction (releases heat), and light provides the energy to initiate the reaction.

* Reduced shelf life: Decomposition reduces the concentration of hydrogen peroxide over time, making it less effective for its intended use. Dark bottles help to protect the solution from light, slowing down the decomposition rate and extending its shelf life.

In addition to dark bottles, other storage practices that help preserve hydrogen peroxide include:

* Cool, dry place: Store hydrogen peroxide in a cool, dry location, as heat also accelerates decomposition.

* Tightly sealed containers: Make sure the bottle is tightly sealed to prevent evaporation and exposure to air.

* Avoid contact with metals: Some metals can catalyze the decomposition of hydrogen peroxide.

* Use within expiry date: Hydrogen peroxide has a limited shelf life. Check the expiry date and dispose of any expired solution properly.