Determination of Copper(Ii) Concentration by Spectrophotometry

2699 WordsMar 23, 201311 Pages
QUANTITATIVE DETERMINATION OF COPPER (II) CONCENTRATION BY SPECTROPHOTOMETRY D.DEL PRADO1, J. BELANO1, M.MAHUSAY2,and M.FRANCISCO2 1 DEPARTMENT OF FOOD SCIENCE AND NUTRITION, COLLEGE OF HOME ECONOMICS 2INSTITUTE OF CHEMISTRY, COLLEGE OF SCIENCE UNIVERSITY OF THE PHLIPPINES, DILIMAN, QUEZON CITY 1101, PHILIPPINES DATE SUBMITTED: 12 MARCH 2013 DATE PERFORMED: 7 MARCH 2013 ------------------------------------------------- ------------------------------------------------- ABSTRACT ------------------------------------------------- ------------------------------------------------- Spectrophotometry has various uses in different fields of science. It can be used in obtaining the concentration and the identity of a solution. In order to test…show more content…
This law is written as: A=abc (3) Where a is the molar absorptivity, b is the path length and c is the concentration of the analyte. Spectrophotmetry is not only confined within the boundaries of chemistry. Its principles have several applications in different branches of science. In biochemistry, it can be used to determine enzyme-catalyzed reactions, whereas in clinical application, it is used to examine blood and tissues. This quantitative method of analysis can also be used in engineering, physics,etc.[2] METHODOLOGY The experiment was initially done by preparing standard solutions of different volumes of Cu(II) stock solution of known concentration including a blank solution composed of ammonia and water. Each volume of the solution was placed in volumetric flasks, and in each flask, same amount of concentrated NH3 was added. The same procedures were also done in the preparation of the diluted unknown Cu(II) solution. Addition of ammonia caused the formation of deeper blue copper-ammonia complex which allowed the spectrophotometer to detect the solution easily due to increase in its absorbance. The formation of the complex is shown by the following chemical reaction: Cu2+ + 4NH3 [Cu(NH3)4]2+ (4) A deficiency in ammonia in the solution would cause the copper-ammonia complex to turn into its hydrated form which would eventually alter the accuracy of the data obtained because of its

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