Reaction Scheme for emitting light from luminol oxidation.
The luminol oxidation reaction with hydrogen peroxide is a classic experiment that results in the emission of light, known as chemiluminescence.

The chemiluminescence reaction involving luminol and hydrogen peroxide is a complex process. The key steps in the mechanism include the following:

1. Formation of Excited-State Luminol:

   • Luminol (C₈H₇N₃O₂) converts into dianion with sodium carbonate (Na₂CO₃) catalyst shown as the first step on the Reaction Scheme.
     
   • The dianion undergoes oxidation in the presence of hydrogen peroxide (H₂O₂), leading to the formation of an intermediate unstable peroxide compound and its decomposition to a triplet (excited) state of dianion.

2. Decay to Ground State with Light Emission:

   • The excited-state luminol then undergoes a process called decay to its ground state.
   • During this decay process, energy is released in the form of light.

3. Role of Catalyst:

   • The sodium carbonate or baking soda often serves as a catalyst, facilitating the reaction by providing an appropriate environment and promoting the formation of reactive intermediates.

The exact details of the reaction pathway can be quite intricate and are often influenced by experimental conditions, such as pH and the presence of other substances. The chemiluminescence observed is a result of the energy released during the decay of the excited-state luminol to its ground state. The reaction is commonly used in forensics to detect the presence of blood, as blood contains iron ions that can act as catalysts for the reaction.