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> Chemistry is colour Issue: 2005-3 Section: Chemistry



Colorimeters, ITIS Cannizzaro, Catania, Italy

Fig 4:

Colorimeter Baush-Lomb

Colorimeter with single “cuvette” with a grating monochromator. It is used in many medical labs.


Fig 5:

Spettrophotometer UV-VIS Perkin Elmer

UV-VIS spectrophoto- meter mono-ray, with two light sources : tungsten lamp(VIS) and deuterium lamp (UV). Prism and grating monochromator .

Photodiode detector. High precision measurement.


Colorimeters, ITIS Cannizzaro, Catania, Italy

Fig 6:

Spettrophotometer UV-VIS Hitachi

UV-VIS spectrophoto- meter double-ray, with two light sources: tungsten and deuterium lamps. This spectrometer has a data computer acquisition and configure it automatically for the operations.

Prism & grating monochromator and Photodiode detector.


Fig 7:

Spettrophotometer Spectonic20 Genesys

Spectrophotomer mono-ray with liquid crystal display, spectral range 8 nm, grating monochromator 1200 lines/mm.

A filter in the colorimeter is used to select the colour of light which the solute absorbs the most, in order to maximise the accuracy of the experiment. Sensors measure the amount of light which has passed through the solution, compared to the amount entering, and a display reads the amount absorbed. A quantitative reading for the concentration of a substance can be found by making up a series of solutions of known concentration of the chemical under study, and plotting a graph of absorbance against concentration. By reading off the absorbance of the specimen substance on the graph, a value for its concentration is found.

Surely, we can have more positive results with other instruments such as spectrometer.

A spectrometer is an optical instrument used to measure properties of light over a specific portion of the electromagnetic spectrum.

The variable measured is most often the light's intensity but could also, for instance, be the polarization state. The independent variable is usually the wavelength of the light, normally expressed as some fraction of a meter, but sometimes expressed as some unit directly proportional to the photon energy, such as wave number or electron volts, which has a reciprocal relationship to wavelength. A spectrometer is used in spectroscopy for producing spectral lines and measuring their wavelengths and intensities. Spectrometer is a term that is applied to instruments that operate over a very wide range of wavelengths, from gamma rays and X-rays into the far infrared.


In general, any particular instrument will operate over a small portion of this total range because of the different techniques used to measure different portions of the spectrum. Below optical frequencies (that is, at microwave, radio, and audio frequencies), the spectrum analyzer is a closely related electronic device.

The use of these instruments and their way of working is really interesting. Try to discover the different steps that lead to the construction of current instruments of analysis is really difficult. Here are some photos of these instruments belonging to Cannizzaro High school in Catania, Italy.


Colorimeters, ITIS Cannizzaro, Catania, Italy

Fig 8:

Colorimeter Hanna

Multiparameter photometer for water analysis with interference filter monochromator and silicium photocell detector.


Fig 9:

Spettrophotometer Varian

Spectrophotometer mono-ray for UV-VIS with xenon lamp, interfaced to PC and data acquisition system. Automatic determination of the straight of calibration.

Stanislao Cannizzaro High School, of Catania represents a point of reference for the formation of professional figures with a good preparation in chemistry, mechanics, computer science and electrical engineering. The institute possesses instruments that go back to the '60 and some sophisticated equipment were acquired in the last decades. They give to students the opportunity to work in group or singularly. Nowadays it is important to redefine the concept of professionalism in the sense of abilities and competences. According to it, the institute has favoured didactic programs and a concept of higher technological content.








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