WHAT IS A COLORIMETRIC?

Colorimetry is a method of chemical analysis are based on the achievement of the amount of color similarity between the sample solution with the standard solution by using a light source polikromatis.

Tools : Colorimeter

This method is based on the absorption of visible light and other radiation energy by a solution.

This method can be applied to the determination of the dye component or components are not colored, but by using the appropriate reagent dye can produce a colored compound which is a function of the content of its components.

• If you have reached the similarity of color means the number of dye molecules absorbing light passed on both sides are same, and this has been used as the basis of calculation.

• Examples are made nitrite solution colored with Sulfanilamide reagent and N- (1-naphthyl) -etilendiamin.?

• PS: The amount of radiation absorbed is proportional to the concentration of absorbent substances in solution.

Colorimetric divided into two methods, namely:

a) Visual colorimetric Using eye as a detector.Visual colorimetric method is a conventional

method and is rarely used because it is not accurate. This is because the eye only as a detector to see the similarity in color, not as a measure of the intensity of absorption.

b) Photometry: Using a photocell detector.

Visual colorimetric analysis methods there are four kinds:

1. Series Standard Method (Method Nesler):In this method, made a series of standard

solutions in the tubes of the same size with the same kind anyway.

2. Balance MethodIn this method is done by comparing the

sample solution with a standard solution which is based on a standard solution of varied thickness.

This method is divided into three, namely:1. - Cylinder System Hehner2. - Bajerum Comparator3. - Dubosq colorimetri

3. dilution method: using a standard substance and a burette containing blank. Standard concentration is diluted with blank until there is similarity in color.

4. The standard method of synthesis: the investigated substance obtained by the addition of a number of standard components against a blank solution until there is similarity in color.

Terms Determining Concentration With Visual Colorimetric Method:A. High Solution Constant (Constant depht

Methods)Divided into two methods:1. Nessler Tube

In this method, used several cylindrical reaction tube. Each tube is filled with a standard solution with a concentration of high scalable and varies with the same solution.

Nessler Tube

2. Bajerum Comparator In this tool, to achieve the color similarity

between the sample solution with the standard solution is done by shifting the solution

Bajerum Comparator

B. High contrast solution (Variable Depth Methods)

Divided into two methods:

1. Hehner TubesHehner the form of a pair of cylindrical tube

with a tap to remove the solution from the cylinder that the color of the solution is more concentrated, so height is changed, in order to have the same color on both cylinders.

Herner Tube

2. Dubosq ColorimeterThe principle of this tools is cooperation

with the colorimeter Nessler tube. A color comparison tool equipped with binoculars.

In this tool color similarity is obtained by regulating the level of ballast (plunger), so that the solution in the vessel height changed to obtain the same color intensity on spiltfield.

Dubosq Colorimete

rbinoculars

Standard

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Terms colorimetric method is the solution should be colorless. If the solution is colorless then performed first with the addition of reagents pengomplekandyes.

While the staining conditions, among others:- Color formed should be stable- Be selective staining reaction- Solution should be transparent- High sensitivity- Re-high accuracy- Color formed to be a function of concentration.

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