Determination of Copper(Ii) Concentration by Spectrophotometry

Only available on StudyMode
  • Download(s) : 385
  • Published : March 15, 2013
Open Document
Text Preview
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 that, an experiment was made using the basic concepts of spectrophotometry. This experiment used the properties of light and how much of it is absorbed by the unknown solution. In relation to this method was the so called principle, the Beer-Lambert’s Law, which was used in getting the relationship of the absorbance and the concentration with one another. Then from the data gathered absorbance and concentration, a calibration curve was made and the equation of the line was determined. The absorbance of an aliquot of unknown copper-ammonia complex solution was then gathered in triplicate and its concentration was determined by the use of the equation determined earlier. The mean absorbance and concentration obtained were 0.2633 and 342.33 ppm, respectively. Using the aliquot factor, the calculated concentration of the unknown solution was 1,711.65 ppm. It was then concluded that this method of analysis was practical in identifying the concentration of Cu(II) solution. -------------------------------------------------

INTRODUCTION

The goals of the experiment were to apply the spectrophotometry in the quantitative analysis of copper (II) solutions, operate a spectrophotometer and measure transmission properties of solutions, and determine an unknown copper (II) concentration in a sample using Beer’s Law. Copper, as known by many, has lots of significance not only in modern technology but also in lives of many organisms. It comprises many enzymes and glycoproteins which supports many biological processes. However, according to many studies copper can also threaten organisms. It can be a toxin to many in the forms of Cu(OH)+, CuCO3,etc. That is why measuring the concentration of copper in many water systems is necessary and this measurement of its concentration can be done using the so called spectrophotometry. [1] Spectrophotometry is branch of analytical chemistry in which the amount of light absorbed by the substance is determined by measuring the intensity of light that passes through sample solution. The basic principle behind this is that chemical solution absorbs or transmits light based on specific range of wavelength. This quantitative method of analysis will never exist without the use of an apparatus called the spectrophotometer. This apparatus has two devices; the spectrometer and photometer. The spectrophotometer normally produces, disperses and measures light, while the photometer measures the intensity of light. The measured intensity of light that passes through the cuvette, the container of a solution, can be related to the transmittance (T), which is the fraction of the light that goes through the sample. Transmittance can be calculated using the following equation: T = ItIo(1)

Where T is the transmittance, It is the intensity of light that passes through the solution, and Io is the light intensity before passing the cuvette. Transmittance can also be related to the absorption by the following equation: A = -log (T)(2)

Where A is the absorbance, which is the amount of photons that is absorbed by the solution. Using the absorbance, the concentration of the solution can be determined by using the Beer’s Law or Beer-Lambert-Bouguer’s Law. This law shows...
tracking img