This article is about a chemical measurement method.
Use of a Colorimeter By Dinshaw Dadachanji; Updated April 27, A colorimeter is any instrument a chemist uses to determine or specify colors. One type of colorimeter can find the concentration of a substance in solution, based on the intensity of color of the solution.
If you are testing a colorless solution, you add a reagent that reacts with the substance, producing a color. This type of colorimeter has a wide range of applications, including laboratory research, environmental analysis of water quality, analysis of soil Colorimeter concentration of a solution, monitoring of hemoglobin content in blood and analysis of chemicals used in various industrial settings.
General Principles When light of a particular color or wavelength range is directed through a chemical solution, some light is absorbed by the solution and some of it is transmitted.
Thus, if you can determine the absorbance of a solution of a substance of unknown concentration and compare it with the absorbance of solutions of known concentrations, you can find the concentration of the substance in the solution being tested.
Mathematical Equations The ratio of the intensity of transmitted light I to the intensity of incident light Io is called transmittance T.
The absorbance of the solution is directly proportional to the concentration c of the absorbing material in solution. For chemists, this is crucially important: Parts of a Colorimeter A colorimeter has three main parts: To produce colored light, the instrument may be equipped with either colored filters or specific LEDs.
The light transmitted by the solution in the cuvette is detected by a photocell, producing a digital or analog signal that can be measured. Some colorimeters are portable and useful for on-site tests, while others are larger, bench-top instruments useful for laboratory testing.
Using the Instrument With a conventional colorimeter, you will need to calibrate the instrument using the solvent alone and use it to determine the absorbance values of several standard solutions containing a solute at known concentrations.
If the solute produces a colorless solution, add a reagent that reacts with the solute and generates a color. Choose the light filter or LED that gives the highest absorbance values. Plot the data to obtain a graph of absorbance versus concentration.
Then use the instrument to find the absorbance of the test solution, and use the graph to find the concentration of the solute in the test solution. Modern digital colorimeters may directly show the concentration of the solute, eliminating the need for most of the above steps.
Uses of Colorimeters Besides being valuable for basic research in chemistry laboratories, colorimeters have many practical applications.
For instance, they are used to test for water quality, by screening for chemicals such as chlorine, fluoride, cyanide, dissolved oxygen, iron, molybdenum, zinc and hydrazine. They are also used to determine the concentrations of plant nutrients such as phosphorus, nitrate and ammonia in the soil or hemoglobin in the blood and to identify substandard and counterfeit drugs.
In addition, they are used by the food industry and by manufacturers of paints and textiles. In these disciplines, a colorimeter checks the quality and consistency of colors in paints and fabrics, to ensure that every batch comes out looking the same.Calculations for Colorimetry. Along with operating the instruments, colorimetry also involves calculations to actually figure out the concentration of a solution from the absorbance measurements made by .
A colorimeter is any instrument a chemist uses to determine or specify colors. One type of colorimeter can find the concentration of a substance in solution, based on the intensity of color of the solution. If you are testing a colorless solution, you add a reagent that reacts with the substance, producing a color.
Lesson 4: Colorimetry. One useful and often used way of determining the concentration of a chemical in a solution, if it has a color, is to measure the intensity of the color and relate the intensity of the color to the concentration of the solution.
concentration of the colored solution absorbs more light (and transmits less) than a solution of lower concentration.
The light sources in the colorimeter are light emitting diodes (LEDs). How do I dilute the primary chlorine standard solution to prepare calibration standards for calibrating my Pocket Colorimeter™ II for chlorine? Document ID (typically 5 to 7) at different concentrations will need to be prepared.
The calibration standards should span the full concentration range of the test. For example, if using a Hach. The Vernier Colorimeter is used to determine the concentration of a solution by analyzing its color intensity. The cuvette slot is designed to accommodate most cuvettes with a 10 millimeter path length.
The Colorimeter measures the amount of light transmitted through a sample at a user-selectable.