An important reaction in the formation of photochemical smog is the photodissociation of NO : NO2 + hv → NO(g) + O(g) The maximum wavelength of light that can cause this reac- tion is 420 nm. (a) In what part of the electromagnetic spec- trum is light with this wavelength found?

Key Concepts

Electromagnetic Spectrum

The electromagnetic spectrum encompasses all types of electromagnetic radiation, arranged by wavelength or frequency. It includes gamma rays, X-rays, ultraviolet light, visible light, infrared radiation, microwaves, and radio waves. The visible spectrum, which is the portion detectable by the human eye, ranges from approximately 400 nm (violet) to 700 nm (red). Understanding where a specific wavelength falls within this spectrum is crucial for identifying its properties and effects.

Photodissociation

Photodissociation is a chemical process in which a molecule absorbs light energy and breaks down into smaller components, often resulting in the formation of free radicals. In the context of the given reaction, the absorption of light by nitrogen dioxide (NO2) leads to its dissociation into nitric oxide (NO) and an oxygen atom (O). This process is significant in atmospheric chemistry, particularly in the formation of pollutants like photochemical smog.

Wavelength and Energy Relationship

The energy of electromagnetic radiation is inversely related to its wavelength, described by the equation E = hc/λ, where E is energy, h is Planck's constant, c is the speed of light, and λ is the wavelength. Shorter wavelengths correspond to higher energy photons, while longer wavelengths have lower energy. This relationship is essential for understanding which wavelengths can initiate specific chemical reactions, such as the photodissociation of NO2 at 420 nm.