The Experimental Procedures for this Lab are Provided as HandoutChemistry 20L Pre-lab Report Guidelines for the Kinetics Experiment The Experimental Procedures for this Lab are Provided as Handout Your pre-lab report should contain: • 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 procedures of the experiment • A calculation of the approximate molarity for solution 3 and the sodium hyprochlorite (assuming 6.15% by weight and volume). You will need to read the lab procedure in order to complete these calculations. SHOW ALL YOUR WORK. • MSDS information for sodium hypochlorite (concentration between 5-6% by weight and volume) and FD&C RED #3 (Erythrosine B) Note: For FD&C Red #3 MSDS, go to the following website and type Erythrosine B in the search engine: http://chemfinder.cambridgesoft.com/ Note: In MSDS, select the site that gives you the MSDS information closest to the concentration or grade listed above for each individual chemical. You should record the following MSDS information in your notebook for the chemicals listed above. (Printouts directly from the Web pages will NOT be accepted!!) (a) Product Name (b) Chemical Formula (c) Formula Weight (d) Melting Point; Boiling Point and Density (e) Health Hazard Data (summarize in your own words) (f) Spill and Disposal procedures (summarize in your own words)Chemistry 20L Pre-lab Report Guidelines for the Kinetics Experiment Use NEW pages in the lab notebook for the following items: • A BLANK table to record the preliminary information on the weight of the dye, bleach concentration, and initial solution absorbances. • Two BLANK 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 during the lab period.Chemistry 20L Post-lab Report Guidelines for the Kinetics Experiment This is a GROUP Report Your report should include: (I) DATA & DATA ANALYSIS (You MUST show ALL your work in order to receive any credit) Write down the names of all the members in the group. Write out the responsibility of each member both for the experiment and for the post-lab report. - Calculate the molarity for the bleach solution. (you may assume that the stock bleach solution contains only NaOCl and that the concentration given on the bottle has a unit of w/v%) Note: Make sure that you are using the w/v% given on the BOTTLE of NaOCl in the lab for the above calculation - Calculate the precise molarity of food-dye solution 1, food-dye solution 2, and food-dye solution 3. - Calculate the initial concentration (molarity) of the food-dye solution in EACH trial. - Using the Beer's law formula, calculate the molar extinction coefficient, ε, for the food dye. You may assume that the diameter of the culture tube to be 1.00cm. (Hint: for this part, use the absorbance you obtained in the lab under “Calibration of Spectrophotometer” to find the molar extinction coefficient of the red food-dye.) - In tabular form, now set up an EXCEL spreadsheet table for EACH trial. Label the columns as time, absorbance, [dye], ln [dye] and 1/[dye]. Note: [ ] means the concentration has a unit of mol/L. (Hint: From Beer’s law, use your experimental absorbances measured at various times together with the molar extinction coefficient of the dye to calculate the [dye] at various times for EACH TRIAL) Provides a legend for each table that gives the experimental condition (temperature, volumes of each reagent etc.)Chemistry 20L Post-lab Report Guidelines for the Kinetics Experiment This is a GROUP Report (II) Graphs Using EXCEL, plot the following 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. EACH of your graphs MUST include a legend for the experimental condition of EACH TRIAL. Print EACH graph on a separate piece of paper. (III) Analysis - From a visual inspection of the plots (see above), select the linear relationships to establish a, the order of the reaction with respect to the dye. Note: if you have trouble determining the order with respect to dye for trial 5 & 6 based on visual inspection, try using trial 3 & 4 as your reference, (Refer to your lecture guide for the relationship between the shape of the graph and the order of the chemical species) - By comparing the ratio of the slopes of the lines for trials 1 and 5, determine b, the order of the reaction with respect to hypochlorite. Refer to the lab handouts page 2 and 3 on how to find the order of the hypochlorite using the ratio of the slopes. - By comparing the ratio of the slopes of the lines for trials 1 and 6, determine b, the order of the reaction with respect to hypochlorite. - Compare the two values of b. Do they agree? - Using the plots that give linear relationships, determine the rate constant (k) for each trial. Do they agree with each other? The rate constants should have the appropriate units. (Hint: Slope = -k [NaOCl]b where b is the order of the bleach you found earlier. [NaOCl] is the INITIAL MOLARITY of the sodium hyprochlorite for the trial )Chemistry 20L Post-lab Report Guidelines for the Kinetics Experiment This is a GROUP Report (IV) Conclusions Summarize your results and the justifications for using the graphs you did to determine the order of the reaction. Write out the experimental rate law for the experiment based on the order of the dye and the order of the sodium hyprochlorite that you obtained in this report. Explain whether the results that you have obtained are consistent with the mechanism proposed at the beginning of this
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