Chem142_Kinetics1_Report_Gradescope_051621_Mac

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CHEM 142

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Chemistry

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Feb 20, 2024

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Page 1 of 7 Name: Abel Tecomahua Quiz Section: CK Lab Partner: Nick Strable Student ID#: 2229544 READ THIS BEFORE PROCEEDING WITH THE DATA ANALYSIS FOR THIS EXPERIMENT: For this lab, you will first evaluate the data for the CV + standards to obtain a value for molar absorptivity ( e ) that you will then use to convert Absorbance data to [CV + ] (Remember: A= e l c; if the calibration curve does not go through 0,0 then you need to include the y-interecept in your calculation of the concentration). You will then evaluate the concentration data as a function of time using the integrated rate law method of determining the orders with respect to each reactant and the rate contant for the reaction at this temperature. You will plot all of the data for the calibration curve and for Run 1. However, for the data in Runs 2-4 and the determination of the order with respect to OH - , INSTEAD OF CREATING ADDITIONAL PLOTS, WE WILL USE A SHORTCUT THAT EMPLOYS FUNCTIONS WITHIN EXCEL TO DETERMINE THE SLOPE AND Y-INTERCEPT FOR A SET OF DATA. For example, to use these functions, click on the cell in which you want the result to appear and enter the following: =SLOPE(A10:A15,B10:B15) =INTERCEPT(A10:A15:B10:B15) In this example, A10:A15 represent an the cells that contain data for the y-axis and B10:B15 represent data for the x-axis. This is a shortcut for generating the slope and y-intercept values without actually creating a plot of the data and generating the trendline equation of y = mx + b. You will create three plots on page 4, using the data from Run 1, to determine the order of the reaction with respect to CV + . Once you know the order of the reaction with respect to CV + , you will perform the necessary "slope" functions for the other three runs to determine k' for each run. When you get to the section for determining the order of the reaction with respect to OH-, you will also need to use the "intercept" function mentioned above. CHEM 142 Experiment #5: Kinetics I (Integrated Rate Law) Goals of this lab: Create and use a calibration curve for the absorbance/concentration relationship for crystal violet Evaluate absorbance versus time measurements to determine the order of a reaction Analyze graphs of data to determine best linear fit Calculate rate constants from best-fit lines and values Assemble a complete kinetic description of the reaction from data gathered Your lab report will be grade on the following criteria using a poor/good/excellent rating system (see the Self- Assessment on the “Reporting Your Results for Exp #5” page of the lab website for more details): Calculations are accurate and complete based on data gathered; proper significant figures and units are used Data collected is reasonable; outliers are identified and possible explanations are reasonable Interpretations of graphs and data are reasonable Reaction orders are determined accurately from data gathered; reasonable conclusions are reached All graphs and tables and clearly and accurately labeled; entire report is typed By signing below, you certify that you have not falsified data, that you have not plagiarized any part of this lab report, and that all calculations and responses other than the reporting of raw data are your own independent work. Failure to sign this declaration will result in 5 points being deducted from your lab score. Signature: __________Abel Tecomahua______________________________ This lab is worth 60 points: 10 points for notebook pages, 50 points for the lab report (Do NOT include your notebook pages when you scan your report for upload into Gradescope.)
Page 2 of 7 NAME: QUIZ SECTION: Part I. Determining the Molar Absorptivity for Crystal Violet Concentration of stock solutions Volume of CV + stock solution needed CV + 1.0E-04 M to make 25 mL of 1.0 x 10 -5 M CV + is OH - 0.10 M CV + 2.5 mL Calibration Curve Data l max, CV + 582.3 nm Dilution Factor [CV + ] (M) Absorbance 10.0 1.0E-06 0.073 4.0 2.5E-06 0.217 2.0 5.0E-06 0.379 1.0 1.0E-05 0.786 Slope of Absorbance versus concentration graph 77989 M -1 y-intercept of Absorbance versus concentration graph 0.0030 Detailed calibration equations: FROM THIS REPORT: FROM THE LQ2 SYSTEM IN LAB: If the slope = e l , what is the molar absorptivity for the CV + at this wavelength? 77989 M -1 cm -1 (Note: if you have two different values based on two different calibration curves, use the equation that is based on your data analysis here in the Excel template, not the one from lab.) Absorbance=77989([CV+]M)0.0030 molar absorptivity, e Absorbance=77977([CV+]M)0.0029071 Note: All sections of this report must be typed y = 77989x + 0.003 R² = 0.9978 0.000 0.100 0.200 0.300 0.400 0.500 0.600 0.700 0.800 0.900 0.0E+00 2.0E-06 4.0E-06 6.0E-06 8.0E-06 1.0E-05 1.2E-05 Absorbance at 582.3 nm CV+ Concentration (M) Calibrations Curve for CV+ Standards
Page 3 of 7 NAME: QUIZ SECTION: Part II. Determining the Rate Law for the CV + + OH - Reaction Table of Volumes and Final Concentrations During Solution Preparation for Runs 1-4 Run # mL of 0.1 M NaOH mL of DI H 2 O mL of 3.0 x 10 -5 M CV + mL Total [CV + ] final , M [NaOH] final , M 1 2 0.5 0.5 3 5.00E-06 0.0667 2 1.5 1 0.5 3 5.00E-06 0.0500 3 1 1.5 0.5 3 5.00E-06 0.0333 4 0.5 2 0.5 3 5.00E-06 0.0167 *[CV+] final and [NaOH] final are the final concentrations after all reagents are mixed and the initial concentration for the start of the reactions slope units for slope y-intercept Student- specific data from pg 2 used in calculations autofill here: 77989 M -1 0.0030 Run 1 Time (s) Absorbance [CV+] t ln[CV+] t 1/[CV+] t 10 0.396 5.04E-06 -12.198 1.98E+05 ORDER WITH RESPECT TO CV + 20 0.348 4.42E-06 -12.329 2.26E+05 Which plot (on the next page) is the most linear? 30 0.336 4.27E-06 -12.364 2.34E+05 40 0.301 3.82E-06 -12.475 2.62E+05 50 0.289 3.67E-06 -12.516 2.73E+05 60 0.268 3.40E-06 -12.593 2.94E+05 70 0.241 3.05E-06 -12.700 3.28E+05 80 0.220 2.78E-06 -12.792 3.59E+05 90 0.203 2.56E-06 -12.874 3.90E+05 100 0.189 2.38E-06 -12.947 4.19E+05 110 0.172 2.17E-06 -13.042 4.62E+05 RUN #1 120 0.153 1.92E-06 -13.162 5.20E+05 130 0.140 1.76E-06 -13.252 5.69E+05 140 0.132 1.65E-06 -13.313 6.05E+05 150 0.122 1.53E-06 -13.393 6.56E+05 160 0.107 1.33E-06 -13.528 7.50E+05 ln[CV+] vs time first order Based on the plots you created on the next page, what is the order of this reaction with respect to CV + ? -0.00860 What is the value of the slope for the most linear plot? What is the psuedo-rate constant (k') for this reaction? 8.60E-03 Show your calculation of the [CV + ] at the first timepoint in Run #1 : 77989([CV+]M)0.0030=Abs 0.396=77989([CV+]M)0.0030 0.393= 77989([CV+]M) [CV+]=5.04E-06 M READ THIS BEFORE PROCEEDING For evaluating the data for Run 1, enter your time and absorbance values, as recorded in your lab notebook during lab, in columns A and B, respectively. In column C, convert the aborbance values to concentration according to the example you provided at the top of this page. In column D, convert the [CV + ] values from column C to ln [CV + ]. In column E, convert the [CV + ] values from column C to 1/[CV + ] . Insert the plots used to determine the order with respect to [CV + ] on the next page, then come back and provide the summary information as requested. Reaction Order Determination for CV +
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Page 4 of 7 NAME: QUIZ SECTION: Place your plot of [CV+] vs time here,making it large enough to cover this box (so that it is easy to read). FOR FULL CREDIT: - plot the correct data on each axis - correctly label each axis and format the axis such that the data being plotted fills the majority of the graph (axes do NOT need to start at 0) - appropriately title the plot - use Excel to add a trendline for the data...be sure to choose the trendline options that "display equation on chart" and "display R-squared on chart" y = -2E-08x + 5E-06 R² = 0.9777 0.00E+00 1.00E-06 2.00E-06 3.00E-06 4.00E-06 5.00E-06 6.00E-06 0 20 40 60 80 100 120 140 160 180 [CV+]t Time(s) Determination of Zero Order Reaction y = -0.0086x - 12.107 R² = 0.9968 -13.600 -13.400 -13.200 -13.000 -12.800 -12.600 -12.400 -12.200 -12.000 0 20 40 60 80 100 120 140 160 180 ln[CV+]t Time(s) Determination of 1st Order Reaction y = 3467.6x + 114388 R² = 0.9558 0.00E+00 1.00E+05 2.00E+05 3.00E+05 4.00E+05 5.00E+05 6.00E+05 7.00E+05 8.00E+05 0 20 40 60 80 100 120 140 160 180 1/[CV+]t Time(s) Determination of 2nd Order Reaction
Page 5 of 7 NAME: QUIZ SECTION: Run 2 Run 3 Time (s) Absorbance [CV+] t f ([CV + ] t) Time (s) Absorbance [CV+] t f ([CV + ] t ) 10 0.340 4.32E-06 -12.352 10 0.367 4.67E-06 -12.275 20 0.321 4.08E-06 -12.410 20 0.350 4.45E-06 -12.323 30 0.300 3.81E-06 -12.479 30 0.335 4.26E-06 -12.367 40 0.283 3.59E-06 -12.537 40 0.319 4.05E-06 -12.416 50 0.260 3.29E-06 -12.623 50 0.304 3.86E-06 -12.465 60 0.242 3.06E-06 -12.696 60 0.289 3.67E-06 -12.516 70 0.224 2.83E-06 -12.774 70 0.276 3.50E-06 -12.563 80 0.210 2.65E-06 -12.840 80 0.264 3.35E-06 -12.608 90 0.186 2.35E-06 -12.963 90 0.251 3.18E-06 -12.659 100 0.174 2.19E-06 -13.031 100 0.238 3.01E-06 -12.713 110 0.158 1.99E-06 -13.129 110 0.225 2.85E-06 -12.770 120 0.145 1.82E-06 -13.217 120 0.214 2.70E-06 -12.820 130 0.134 1.68E-06 -13.297 130 0.204 2.58E-06 -12.869 140 0.125 1.56E-06 -13.368 140 0.194 2.45E-06 -12.920 150 0.116 1.45E-06 -13.445 150 0.185 2.33E-06 -12.968 160 0.176 2.22E-06 -13.019 170 0.167 2.10E-06 -13.073 180 0.160 2.01E-06 -13.116 190 0.151 1.90E-06 -13.175 200 0.144 1.81E-06 -13.224 210 0.135 1.69E-06 -13.290 220 0.129 1.61E-06 -13.336 230 0.122 1.53E-06 -13.393 240 0.115 1.44E-06 -13.454 250 0.110 1.37E-06 -13.500 RUN #2 What is the value of the slope for the most linear plot? What is the psuedo-rate constant (k') for this reaction? RUN #3 What is the value of the slope for the most linear plot? What is the psuedo-rate constant (k') for this reaction? -0.00807 8.07E-03 -0.00512 5.12E-03
Page 6 of 7 NAME: QUIZ SECTION: Run 4 Time (s) Absorbance [CV + ] t f ([CV + ] t ) 10 0.420 5.35E-06 -12.139 RUN #4 20 0.409 5.21E-06 -12.166 What is the value of the slope for the most linear plot? 30 0.400 5.09E-06 -12.188 40 0.390 4.96E-06 -12.214 50 0.380 4.83E-06 -12.240 60 0.370 4.71E-06 -12.267 What is the psuedo-rate constant (k') for this reaction? 70 0.361 4.59E-06 -12.292 80 0.351 4.46E-06 -12.320 90 0.343 4.36E-06 -12.343 100 0.334 4.24E-06 -12.370 110 0.325 4.13E-06 -12.398 120 0.316 4.01E-06 -12.426 130 0.308 3.91E-06 -12.452 140 0.300 3.81E-06 -12.479 150 0.293 3.72E-06 -12.502 160 0.285 3.62E-06 -12.530 170 0.278 3.53E-06 -12.555 180 0.272 3.45E-06 -12.578 190 0.264 3.35E-06 -12.608 200 0.258 3.27E-06 -12.631 210 0.252 3.19E-06 -12.655 220 0.245 3.10E-06 -12.683 230 0.238 3.01E-06 -12.713 240 0.232 2.94E-06 -12.739 250 0.226 2.86E-06 -12.765 260 0.221 2.79E-06 -12.788 270 0.215 2.72E-06 -12.816 Run # [OH - ] k' ln[OH - ] ln(k') 280 0.209 2.64E-06 -12.844 1 0.0667 8.60E-03 -2.708 -4.75599308 290 0.204 2.58E-06 -12.869 2 0.0500 8.07E-03 -2.996 -4.8196018 300 0.199 2.51E-06 -12.894 3 0.0333 5.12E-03 -3.401 -5.27460084 310 0.193 2.44E-06 -12.925 4 0.0167 2.63E-03 -4.094 -5.94077143 320 0.188 2.37E-06 -12.952 330 0.183 2.31E-06 -12.979 slope 0.899 340 0.178 2.24E-06 -13.008 y-int -2.23 350 0.174 2.19E-06 -13.031 360 0.169 2.13E-06 -13.060 Order of the reaction with respect to [OH - ]: First Order Rate constant for the overall reaction, k: 0.108 Units for k: M^-1s^-1 -0.00263 2.63E-03 ln(k') vs. ln([OH - ]) autofill from earlier in report Values for [OH - ] and k' Reaction Order Determination for OH - Show your calculation of the rate constant for the overall reaction. ln(k)=y intercept k=e^(y intercept) k=e^(-2.23) k=.108 Consult the "Helpful Information" section in the introductory pages for this experiment in the lab manual for help with this last section of data analysis. As explained in the Instruction box on page 1 of the template, for the slope and y-intercept calculations you will use the functions in Excel rather than creating a plot.
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Page 7 of 7 NAME: QUIZ SECTION: Results from earlier in the report autofill here: Order wrt CV+ Unrounded Order wrt OH- Overall rate constant Units for overall rate constant first order First Order 0.108 M^-1s^-1 Results and Discussion 1. Based on your data, write the complete rate law, including the value and units for the rate constant. Rate=K[A][B] Rate=0.108M^-1s^-1[CV+][OH-] Laboratory Waste Evaluation Laboratory waste is considered anything generated during an experiment that is disposed of down the sewer drain, thrown in the garbage, collected in a container for disposal by the UW Environmental Health & Safety department, or released into the environment. Based on the written lab procedure and your actions during the lab, list the identity and approximate amount (mass or volume) of waste that you generated while performing this experiment. 6mL of CH+ M-1 25mL of 1.05E-05 CV+ 2mL of 3.0E-05M CV+ 10 mL of 0.1M NaOH 50mL of Di water 2. The literature values of the orders with respect to CV + are and OH - are 1 and 1, respectively. Calculate your % error for the experimental value for the order with respect to [OH - ]. Discuss your largest sources of error. %error=|0.108-1|/1=0.892*100=89.2 %error The measurements of the solutions may have been off by the smallest amount, which could have resulted in a considerably different concentration. Additionally, the concentration may alter if we added too much or too little Di water.