Chemistry 14BL Fall 2002 Report Guidelines for Kinetics of FD C Red 3 The following guidelines are reproduced directly from the assignment that was prepared for this quarter s class There is no quiz for this assignment PRE LAB WORK INDIVIDUAL Introduction In preparing for lab set up your notebook with the following information The title of the experiment A reference identifying the procedure handout A short introduction summarizing the goals of the experiment and the techniques that you will use in the experiment A brief flow chart summary of the key procedures of the experiment MSDS information for sodium hypochlorite solutions and erythrocin B sodium A table to record the preliminary information on dye weight bleach concentration and initial solution absorbances Two data tables to record the measured absorbances and times for the various rate runs Leave space for a heading that will identify the trial number and the experimental conditions for the trial IN LAB WORK Data Individual Record your partner s name and the agreed upon allocation of responsibility for the experiment and the report Indicate in whose notebooks the various data trials will be recorded All notebooks need to have at least two trials of original data Record the weight of food coloring used to prepare Solution 1 Record the concentration of the bleach solution Record the absorbance of Solution 3 From this point on the data is acquired and shared as a group In tabular format record the time and absorbance readings for each of the six rate trials Be sure the headings for the tables reflect the experimental conditions for the trial POST LAB NOTEBOOK REPORT GROUP Calculations Calculate the molar concentrations of the three dye solutions The molecular weight of FD C Red 3 is 879 9 g mol Using Beers Law A bc determine the molar extinction coefficient for FD C Red 3 Use the concentration and absorbance of Solution 3 and assume the diameter of the culture tube the path length is 1 cm Calculate the initial concentration of dye in each trial At time 0 Set up a spreadsheet table for each trial Label the columns time Absorbance dye ln dye 1 dye Note means concentration in mol L Calculate the data for each cell Note Use the measured absorbance of the solution during the trial the calculated extinction coefficient for the dye and a path length of 1cm to determine the dye during the rate runs Graphs Prepare three graphs for each trial dye vs time ln dye vs time 1 dye vs time Be sure to title your graphs and label the axes including units Analysis From a visual inspection of these plots select the linear relationships to establish a the order of the reaction with respect to the dye Using the plots that give linear relationships determine the rate constant for each trial By comparing the slopes of the lines for trials 1 5 and 6 determine b the order of the reaction with respect to hypochlorite Conclusions Summarize your results and the justifications for using the graphs you did to determine the order of the reaction Kinetics studies can disprove a proposed mechanism but can never prove a mechanism Explain whether the results that you have obtained are consistent with the mechanism proposed at the beginning of this assignment
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