colorimetry
colorimetry [kul΄ərim′ə trē]
n.
the analysis or measurement of color by means of a colorimeter
colorimetric [kul΄ər ə me′trik]
adj.
colorimetrically
adv.

* * *

See colorimetric.

* * *

Measurement of the intensity of electromagnetic radiation in the visible spectrum transmitted through a solution or transparent solid.

It is used to identify and determine the concentrations of substances that absorb light of a specific wavelength or colour according to Lambert's law, which relates the amount of light absorbed to the distance traveled through the absorbing medium, and Beer's law, relating it to the concentration of absorbing substance in the coloured solution. A photocell is often used to measure the amount of light transmitted through a glass tube containing the solution to be analyzed; the result is compared with results from a similar tube containing solvent alone. Most elements and many compounds, in appropriately treated samples, may be identified by colorimetry or spectrophotometry, a closely related technique.

* * *

      measurement of the wavelength and the intensity of electromagnetic radiation in the visible region of the spectrum. It is used extensively for identification and determination of concentrations of substances that absorb light. Two fundamental laws are applied: that of a French scientist, Pierre Bouguer, which is also known as Lambert's law, relates the amount of light absorbed and the distance it travels through an absorbing medium; and Beer's law relates light absorption and the concentration of the absorbing substance. The two laws may be combined and expressed by the equation log I0/I = kcd, where I0 = intensity of the incident beam of light, I = transmitted intensity, c = the concentration of absorbing substance, d = the distance through the absorbing solution, and k = a constant, dependent upon the absorbing substance, the wavelength of light used, and the units used to specify c and d.

      A simple application of this expression is found in comparing intensities of radiation transmitted through layers of different thicknesses of two solutions of the same absorbing substance, one with a known concentration, the other unknown. If the same incident intensity is used and if the thicknesses of the two solutions are adjusted so that the transmitted intensities are equal, then the concentration of the unknown (c2) can be expressed by the ratio of the thicknesses of the two solutions, d1/d2, times the known concentration (c1). If a photoelectric cell instead of the eye is used to compare intensities, the instrument is called a photoelectric colorimeter.

      In colorimetry, frequently the entire visible spectrum (white light) is used, and consequently the complementary colour of the one absorbed is observed as transmitted light. If monochromatic light or a narrow band of radiation is used, the instrument is called a spectrophotometer. It is not limited to the visible spectrum and is often employed to make measurements in the ultraviolet and infrared regions. The spectrophotometer has largely replaced the colorimeter.

      Most of the chemical elements and a large number of compounds may be determined colorimetrically or spectrophotometrically, frequently at concentrations smaller than one part of the constituent in several hundred million parts of solution.

* * *


Universalium. 2010.

Look at other dictionaries:

  • Colorimetry — Col or*im e*try, n. [See {Colorimeter}.] 1. The quantitative determination of the depth of color of a substance. [Webster 1913 Suppl.] 2. A method of quantitative chemical analysis based upon the comparison of the depth of color of a solution… …   The Collaborative International Dictionary of English

  • colorimetry — [kul΄ərim′ə trē] n. the analysis or measurement of color by means of a colorimeter colorimetric [kul΄ər ə me′trik] adj. colorimetrically adv …   English World dictionary

  • Colorimetry — This article is about measurement of color. For use in chemistry, see Colorimetry (chemical method). Not to be confused with Calorimetry. Colorimetry is the science and technology used to quantify and describe physically the human color… …   Wikipedia

  • colorimetry —  Photometric Analysis, Colorimetry  Фотометрический анализ   Метод качественного и количественного анализа, основанный на избирательном поглощении инфракрасного, видимого или ультрафиолетового излучения молекулами определяемого компонента или его …   Толковый англо-русский словарь по нанотехнологии. - М.

  • colorimetry — kolorimetrija statusas T sritis Standartizacija ir metrologija apibrėžtis Cheminės analizės metodas, pagrįstas tirpalo medžiagų regimosios spinduliuotės sugerties matavimu tam tikroje bangų ilgių srityje. atitikmenys: angl. colorimetry vok.… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • colorimetry — kolorimetrija statusas T sritis Standartizacija ir metrologija apibrėžtis Spalvos matavimas kolorimetru. atitikmenys: angl. colorimetry vok. Farbmessung, f; Farbmetrik, f; Kolorimetrie, f rus. колориметрия, f pranc. colorimétrie, f …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • colorimetry — kolorimetrija statusas T sritis Standartizacija ir metrologija apibrėžtis Šviesos ir įvairių medžiagų spalvos nustatymo metodų visuma. atitikmenys: angl. colorimetry vok. Farbmessung, f; Farbmetrik, f; Kolorimetrie, f rus. колориметрия, f pranc.… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • colorimetry — kolorimetrija statusas T sritis chemija apibrėžtis Analizės metodas, pagrįstas regimosios spinduliuotės absorbcijos matavimu. atitikmenys: angl. colorimetry rus. колориметрия …   Chemijos terminų aiškinamasis žodynas

  • colorimetry — kolorimetrija statusas T sritis fizika atitikmenys: angl. chromatometry; colorimetry vok. Farbmessung, f; Kolorimetrie, f rus. колориметрия, f pranc. colorimétrie, f …   Fizikos terminų žodynas

  • colorimetry — noun see colorimeter …   New Collegiate Dictionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”