HXCCDdMp+ad{3p\P>n 7hf*v[g =&X!5;$5L/9e 5 %PDF-1.3 lowest-energy electronic state (called the ground state) to a higher-energy electronic state Garland, C.; Nibler, J.; Shoemaker, D. Experiments in Physical Chemistry ; /Names A: Pinacyanol chloride, MM = 388 g/mol Atkins, J,: Paula, J. 0000007892 00000 n Save your spectra as ASCII text files for importing into Excel. Truman State University If the particle in a box is used to represent these molecules then the pi electrons need to be distributed into the box. The general approach to this experiment is adapted from D. P. Shoemaker, C. W. Garland, and J. W. Nibler, Experiments in Physical Chemistry, 6th edition, McGraw Hill Co. Inc, NY, 1996, p378. A holmium oxide (Buck Scientific) test was performed to calibrate the spectrophotometer. obj subscribers only). Educ. 0000000967 00000 n /Pages 8 $('#commentText').css('display', 'none'); The region that pi electrons occupied is said to be the. In conclusion, we find that PIB is predictive as long as we apply it to a homologous series. Make plots of the absorbance spectra for dyes A F. You may combine the plots in one or two page graphs. The absolute percent error between theoretical and experimental max absorbed for dye 4 is much larger than that of dyes 1, 2, and 3. lodide). R Therefore, if = 1, this This principle of expansion will be repeatedly utilized in the quantum mechanical treatment of more complex chemical systems later in the semester. Particle in a box Pre-Lecture Assignment You must show all working to receive full credit. The number of -electron pairs equals k + 3. 0000034293 00000 n Although the theoretical max gives a similar trend we see in our max measurements, it seems that there is a good agreement between the experimental and theoretical max for dyes 1, 2, and 3, and not for dye 4. A higher level means a higher potential energy. 0 /Nums An in-house MATLAB subroutine was used to determine the optimum gamma value and calculate the PIB or theoretical wavelengths of the series of four dyes. $('#comments').css('display', 'none'); The dyes can be run in any order. Carry out the necessary calculations and propagate the errors involved to the final answer. It is advisable not to try to do the peak picking in Excel; it is fairly tedious. The theoretical max also shows a similar trend. 2,2-cynide by treating the system as a 1-D particle in a box. 0000004510 00000 n Assume that each bond has a length of 0.139 nm and estimate the length of the box from the number of bonds. Soltzberg, L. J. J. Chem. Representative members of the cyanine family of conjugated dyes. In the case of electrons in the particle in a box there are two quantum numbers, n and spin. The energy level of a particle in a 1D box is expressed as: 2 2 =withn=1,2,3.. 8 2 = 9.109x10-31kg = mass of an electron = 6.626x10-34Js = Plank's constant L = Length of the box 2. It was also seen that the lengths of the box calculated increase with the number of carbon atoms. My Final Lab Report in College: The Absorption Spectra of Conjugated Dyes Figure 1. Three things need to be considered to calculate the energy changes from Equation 5. Our observation suggests that PIB is predictive only when it is applied to a homologous series, wherein all compounds in the series have similar functional groups and similar chemical properties, with the only difference here being an increase in carbon number. In reality the pi electrons may be considered to reside across the system of conjugated pi-bond system that extends from one nitrogen atom to the other, Figure 1. In the experiment the length of the conjugated pi-system will be calculated for each dye from measurements of abs and Equation (11). Calculate the length of the conjugated pi-system, L, for each of the dyes from the measured . 0 Farrell, J. J. J. Chem. Moog, R. S. J. Chem. Hence, gamma should be calculated using only compounds from a homologous series (9). ( G o o g l e) 0000006031 00000 n Any group that produces more waste than that will be penalized accordingly. To verify our hypothesis, we plot the literature and theoretical max against p for dye 4 along with 1,1-diethyl-4,4-cyanine iodide (dye 5) and 1,1-diethyl-4,4-dicarbocyanine iodide (dye 6), two dyes that fall within the homologous series containing dye 4 (8). { "4.01:_Pre-lab_Assignment" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "4.02:_Introduction" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "4.03:_Experimental_and_Discussion_Questions" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "4.04:_References" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "4.05:_Appendix_A_-_Use_of_the_Agilent_100_Series_UV-Vis_Spectrophotometer" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, { "00:_Front_Matter" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "01:_Orientation_to_this_course" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "02:_Introduction_to_Matlab_for_Pchem_Lab" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "03:_The_Treatment_of_Experimental_Error" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "04:_Absorption_Spectrum_of_Conjugated_Dyes" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "05:_Rotation-Vibration_Spectrum_of_HCl_and_DCl" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "06:_Calorimetry" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "07:_Kinetics" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "08:_Molecular_Electronic_Structure_Calculations" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "zz:_Back_Matter" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, { "CHEM301L_-_Physical_Chemistry_Lab_Manual" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "CHEM310L_-_Physical_Chemistry_I_Lab_Manual" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", CHEM_110_Honors_Writing_Projects : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Chem_201_(Organic_Chemistry_I)_-_Cox" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "CHEM_210D:_Modern_Applications_of_Chemistry" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "CHEM_401L:_Analytical_Chemistry_Lab_Manual" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, 4: Absorption Spectrum of Conjugated Dyes, [ "article:topic-guide", "source[1]-chem-369883" ], https://chem.libretexts.org/@app/auth/3/login?returnto=https%3A%2F%2Fchem.libretexts.org%2FCourses%2FDuke_University%2FCHEM301L_-_Physical_Chemistry_Lab_Manual%2F04%253A_Absorption_Spectrum_of_Conjugated_Dyes, \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}}}\) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\).