Color Color Color (American English), or colour (Commonwealth English), is the characteristic of human visual perception described through color "categories", with names such as red, orange, yellow, green, blue, or purple. This perception of color derives from the stimulation of cone cells in the human eye by electromagnetic radiation in the visible spectrum. Color categories and physical specifications of color are associated with objects through the wavelength of the light that is reflected from them. This reflection is governed by the object's physical properties such as light absorption, emission spectra, etc. By defining a color space, colors can be identified numerically
Color reaction is required because standard colorimeters cannot operate below a wavelength of 400 nanometers. It is also necessary to use fused quartz cuvettes because glass is opaque to ultraviolet. Many different color reagents have been developed for determining the concentrations of different substances. For example, Nessler's reagent can be used to determine the concentration of a solution of ammonia. In thin layer chromatography (TLC) color reactions are frequently used to detect compound spots by dipping the plate into the reagent or by spraying the reagent onto the plates. Color reaction In chemistry, a color reaction or colour reaction is a chemical