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The color of chemicals is a physical property of chemicals that in most cases comes from the excitation of electrons due to an absorption of energy performed by the chemical. The study of chemical structure by means of energy absorption and release is generally referred to as spectroscopy .
Examples of acid dye are Alizarine Pure Blue B, Acid red 88, etc. Basic dyes are water-soluble cationic dyes that are mainly applied to acrylic fibers , but find some use for wool and silk. Usually acetic acid is added to the dye bath to help the uptake of the dye onto the fiber.
In chemistry, solvatochromism is the phenomenon observed when the colour of a solution is different when the solute is dissolved in different solvents. [1] [2] Reichardt's dye dissolved in different solvents. The solvatochromic effect is the way the spectrum of a substance (the solute) varies when the substance is dissolved in a variety of ...
Leaves change color in the fall because their chromophores (chlorophyll molecules) break down and stop absorbing red and blue light. [1] A chromophore is a molecule which absorbs light at a particular wavelength and reflects color as a result. Chromophores are commonly referred to as colored molecules for this reason.
Several of the CPK colors refer mnemonically to colors of the pure elements or notable compound. For example, hydrogen is a colorless gas, carbon as charcoal, graphite or coke is black, sulfur powder is yellow, chlorine is a greenish gas, bromine is a dark red liquid, iodine in ether is violet, amorphous phosphorus is red, rust is dark orange-red, etc.
The Munsell system describes a color in three dimensions, hue, value (lightness), and chroma (color purity), where chroma is the difference from gray at a given hue and value. By the middle 20th century, standardized methods for pigment chemistry were available, part of an international movement to create such standards in industry.
Another example of a leuco dye is the crystal violet lactone, which in its lactone form is colorless or slightly yellowish, but in low pH, when it is protonated, it becomes intensely violet. [1] Other examples are phenolphthalein and thymolphthalein , colorless in acidic to neutral pH, but becoming pink and blue in alkaline environment.
In chemistry, chromism is a process that induces a change, often reversible, in the colors of compounds.In most cases, chromism is based on a change in the electron states of molecules, especially the π- or d-electron state, so this phenomenon is induced by various external stimuli which can alter the electron density of substances.