03pSpectrodyes

03pSpectrodyes - Spectrophotometry Spectrophotometry...

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Unformatted text preview: Spectrophotometry Spectrophotometry & Beers Law of F of F o o o o d d D D y y e e s s Last Update: 02/02/10 07:09 How is the absorption/transmission of light measured? How is the intensity of color related to the concentration of colored solutions? What is the quantitative basis for the color of substances? ? QUESTIONS ? ? QUESTIONS ? What considerations go into graphing experimental data? Questions Concepts: Concentration Transmittance Absorbance Analytical Wavelength Beers Law Blank Absorptivity Electromagnetic Spectrum Slopes Techniques: Quantitative dilution Visible Spectroscopy Graphing Plotting /Curve fitting Apparatus: Spectronic 20 Pipet Syringe Recording Spectrophotometer For a simple, transparent, C O L O R E D material, e.g. Can plot a graph showing the percent of light of each discrete C O L O R (wavelength, ) transmitted by the solution BACKGROUND BACKGROUND Transmitted light VIOLET VIOLET CLEAR SOLUTION Incident white light I t ( ) I i ( ) I t ( ) 100 X I i ( ) %T( ) = R O Y G B V R OYG B V Percent Transmittance Transmittance of White Light by a Violet Solution 10 20 30 40 50 60 70 80 90 100 WAVELENGTH (nm) % TRANSMITTED Violet Red Green Yellow Blue % Transmitted % Transmittance of White Light by a Violet Solution Absorbance of White Light by Violet Solution 10 20 30 40 50 60 70 80 90 100 WAVELENGTH (nm) Violet Red Blue Green % Absorbed Yellow % Absorbed of White Light by a Violet Solution % Absorbed = 100% - % Transmitted VISIBLE AND ULTRAVIOLET : Electronic structure of molecules INFRARED REGION : Vibrations of molecules What determines the WAVELENGTHS of light that substances absorb? What determines INTENSITY of absorption? EFFICIENCY of INTERACTION between Molecules & Electromagnetic Radiation 100 nm 800 nm 800 nm 100 m Which DEVICE measures this phenomenon?...
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This note was uploaded on 02/01/2010 for the course CHE 133 taught by Professor Robertschneider during the Winter '08 term at SUNY Stony Brook.

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03pSpectrodyes - Spectrophotometry Spectrophotometry...

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