Spectrophotometry
SPECTROPHOTOMETRY
Herman, Harmon Chris T.
1Prof. Meynard Austria, of Chemical Engineering, Chemistry and Biotechnology, Mapua Institute of Technology, Chm171L/A1, School of Chemical Engineering, Chemistry and Biotechnology, Mapua Institute of Technology, Experiment # 4
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ABSTRACT
The objectives of this experiment are to examine the components of a simple spectrophotometer- the Jenway 6100 & Perkin Elmer Lambda 40. As well as to determine the absorption spectrum of a solution and to prepare a Beer’s Law Plot. In the spectrometer used, the light source is imaged upon the sample. A fraction of the light is transmitted or reflected from the sample. The light from the sample is imaged upon the entrance slit of the monochromator. The monochromator separates the wavelengths of light and focuses each of them onto the photo detector sequentially. The absorption spectrum is determined to select the optimal wavelength for analyzing the cobalt (II) nitrate. The optimal wavelength for measuring absorbance is that wavelength that is most absorbed by the compound. The Beer’s Law Plot showed and differentiate the proportionality of the Concentration vs Absorbance graph and the Wavelength vs Absorbance graph. The first graph is linear while the latter one is characterized by the wavelength at which the absorbance is the at the greatest.
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INTRODUCTION
A spectrophotometer or colorimeter makes use of the transmission of light through a solution to determine the concentration of a solute within the solution. A spectrophotometer differs from a colorimeter in the manner in which light is separated into its component wavelengths. A spectrophotometer uses a prism to separate light and a colorimeter uses filters.
Both are based on a simple design of passing light of a known wavelength through a sample and measuring the amount of light energy that is transmitted. This is accomplished by placing a photocell on the other side of the sample. All
Herman, Harmon Chris T.
1Prof. Meynard Austria, of Chemical Engineering, Chemistry and Biotechnology, Mapua Institute of Technology, Chm171L/A1, School of Chemical Engineering, Chemistry and Biotechnology, Mapua Institute of Technology, Experiment # 4
[pic]
ABSTRACT
The objectives of this experiment are to examine the components of a simple spectrophotometer- the Jenway 6100 & Perkin Elmer Lambda 40. As well as to determine the absorption spectrum of a solution and to prepare a Beer’s Law Plot. In the spectrometer used, the light source is imaged upon the sample. A fraction of the light is transmitted or reflected from the sample. The light from the sample is imaged upon the entrance slit of the monochromator. The monochromator separates the wavelengths of light and focuses each of them onto the photo detector sequentially. The absorption spectrum is determined to select the optimal wavelength for analyzing the cobalt (II) nitrate. The optimal wavelength for measuring absorbance is that wavelength that is most absorbed by the compound. The Beer’s Law Plot showed and differentiate the proportionality of the Concentration vs Absorbance graph and the Wavelength vs Absorbance graph. The first graph is linear while the latter one is characterized by the wavelength at which the absorbance is the at the greatest.
[pic]
INTRODUCTION
A spectrophotometer or colorimeter makes use of the transmission of light through a solution to determine the concentration of a solute within the solution. A spectrophotometer differs from a colorimeter in the manner in which light is separated into its component wavelengths. A spectrophotometer uses a prism to separate light and a colorimeter uses filters.
Both are based on a simple design of passing light of a known wavelength through a sample and measuring the amount of light energy that is transmitted. This is accomplished by placing a photocell on the other side of the sample. All
References: 1. Glenn Elert. "The Electromagnetic Spectrum, The Physics Hypertextbook". Hypertextbook.com. Retrieved 2010-10-16. 2. Allen, D., Cooksey, C., & Tsai, B. (2010, October 5). Spectrophotometry 3. J. D. J. Ingle and S. R. Crouch, Spectrochemical Analysis, Prentice Hall, New Jersey (1988) 4. International Union of Pure and Applied Chemistry (IUPAC) Glossary of terms used in photochemistry. Recommendations 1988 (Braslavsky, S. E. & Houk, K. N., eds) Pure Appl. Chem. 60, 1055-1106 (1988). An updated version, edited by J. W. Verhoeven, has appeared in Pure Appl. Chem. 68, 2223-2286 (1996)