CHEM 20L Winter 2003 Report Guideline for Experiment #2 Pre-lab is due at the beginning of the lab section. Refer to laboratory syllabus for the due date for both the pre-lab and post-lab report. Both pre-lab and post-lab reports MUST be written inside your LAB NOTEBOOK. The experimental procedure for this experiment is provided as handouts. (I) Pre-lab Guideline (i) Title of the experiment (ii) Reference (i.e. complete reference of the experiment including title of the lab manual, author, edition and page number of the experiment in the manual etc.) (iii) Short introduction (Summarize in a few sentences about the background and the goal of the experiment. Outline the kinds of technique that you will use in the experiment) (iv) Procedures (flowchart format) (v) Pre-lab study questions (complete ONLY#1,2,4,5 & 6 on page 4 of the handouts) (Must show all work for FULL credit) Note: For question 2, you may assume that for EACH dilution process, each piece of equipment can ONLY be used once and you can also assume that no combinations are allowed for the same kind of equipment (i.e. you don't need to worry about the combination of a 10-mL and a 5-mL pipet). (vi) Data/observations (start a NEW page in your notebook for this section) Set up tables but leave blank. (refer to item #10 on page 5 of the handouts) There is NO MSDS for this pre-lab report!CHEM 20L Winter 2003 Report Guideline for Experiment #2 Pre-lab is due at the beginning of the lab section. Refer to laboratory syllabus for the due date for both the pre-lab and post-lab report. Both pre-lab and post-lab reports MUST be written inside your LAB NOTEBOOK. The experimental procedure for this experiment is provided as handouts. Post-lab Guideline (This is a GROUP Report) (i.e. TURN IN ONLY ONE POST-LAB PER GROUP) Useful definitions for the report: w/v% is defined as weight of solute/100 mL of solution ppm is defined as mg of solute/L of solution ppb is defined as µg of solute / L of solution (A) Data & Data Analysis Write out the name of each group member on your report as well as the individual responsibility when performing the experiment and writing the report (i) Set up a data table with columns for wavelengths you collected for your spectrum and the absorbances for the solutions you collected. Fill in the experimental data on the data table. At this point, you will only have data entries for one row and one column of the data table. You will fill in the rest of the data table later on in the report. (ii) Description of the serial dilution procedure and rationale for the design of the dilution procedures (iii) Calculate the concentrations (only molarity , ppm and w/v%) for all the solutions based only on the procedures that you designed. (iv) The value for the molar extinction coefficient for the Brilliant Blue FCF is reported in the literature (at 620nm) as 1.38X105 M-1 cm-1. Using this value and the measured absorbances (at 620nm) you collected in the lab, calculate the concentrations (M) for each of the 3 most diluted solutions. You may assume L=1cm. (B) Graphs (i) Using millimeter graph paper, plot a Beer’s law calibration curve (concentration (M) as x-axis and absorbance as y-axis) based only on the calculated concentrations and measured absorbance for the three most diluted solutions at 620nm. (ii) Using millimeter graph paper, plot the spectrum (use absorbance as y-axis and wavelengths as x-axis) for one of the diluted solutions that you chose to measure during the lab.CHEM 20L Winter 2003 Report Guideline for Experiment #2 Pre-lab is due at the beginning of the lab section. Refer to laboratory syllabus for the due date for both the pre-lab and post-lab report. Both pre-lab and post-lab reports MUST be written inside your LAB NOTEBOOK. The experimental procedure for this experiment is provided as handouts. Post-lab Guideline (This is a GROUP Report) (i.e. TURN IN ONLY ONE POST-LAB PER GROUP) (C) Error Analysis (refer to example in lecture guide #1) (i) Calculate the % Inherent Error (molarity only) for the FINAL (i.e. the most diluted one) solution that you prepared (Must show all work for full credit) Note: Absolute errors for all the lab equipment are listed on p.31 of the manual. You may assume the absolute error in the 1-ml plastic syringe to be ± 0.05ml. (ii) Calculate the % difference between the calculated concentrations (part (iii) under Data and Data Analysis) and the measured values (part (iv) under Data and Data Analysis) for the three most diluted solutions at 620nm. (D) Discussions and Extrapolation (refer to page 7 of the handouts) (E) Practical Considerations (refer to page 8 of the handouts) (F) Conclusions Explain the effect of wavelengths on the Beer’s law calibration graph (i.e. the one with absorbances and
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