Chem 20L Fall 2003Refer to the lecture guide on error analysis for Beer's LawChem 20L Fall 2003 Report Guideline for Experiment 3 (Cigarette Experiment) Pre-lab report is due at the beginning of the lab section. Pre-lab MUST be written inside your lab notebook. (I) Pre-lab Report Guideline - Title of the experiment - Reference of procedures - Introduction - Procedural flowchart (see question #2 on page 51 under "Pre-lab Assignment") - MSDS information (refer to the MSDS handout for details) The following chemicals will require you to use the MSDS database on the Web (refer to the MSDS handout for details on how to do the search on the Web): Sodium Nitrite (Reagent Grade) 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) - set up blank DATA TABLES Follow instructions for question 1 on p.51 (under "Pre-lab assignment") of your lab manual. (Make sure that you SEPARATE the blank data table (i.e. use a NEW page for the data table) with the rest of the pre-lab)Chem 20L Fall 2003 Report Guideline for Experiment 3 (Cigarette Experiment) Refer to laboratory syllabus for the due date of the post-lab report. Post-lab MUST be written inside your lab notebook (with the exception of graphs) (II) Post-lab Report Guideline This is a GROUP REPORT (i.e. ONE post-lab from EACH group) (A) Data - Write down the names of the all the group members and their responsibilities in writing the post-lab report and during the experiment. - Orderly record of data (see page 53 under "Data" section) - Data tables should have proper titles/labels (B) Data and Error Analysis (MUST SHOW ALL WORK FOR FULL CREDIT) Particulates - calculate the weight of the particulates collected on the filter membrane - total weight of the particulates in the cigarette - calculate the weight of the particulates per millimeter of cigarette smoked - concentration of particulates in cigarette smoke (see equation 10 on p.53) - Calculate the % relative error (or % inherent error) in the weight of the particulates in cigarette Note: Assume absolute error of the ruler is +/- 0.1 cm. (C) Calculations and Beer's Law Calibration Graph for NOx - calculate concentrations for all the standard solutions - plot the Beer’s law calibration graph by using the standard solutions. The x-axis should be the concentration of nitrite ion in unit of microgram/mL. The y-axis should be the Absorbance. Draw a best-fit line through the standards. Your best-fit line should go through (0,0). Your graph must have proper title, labels and units. Data points must be clearly marked. Make sure you use the correct type of graph paper (mm graph paper), if you are NOT using EXCEL to plot the graph. If you use EXCEL, make sure that the gridlines are set properly. - slope of the line (with proper unit) (indicate which two points on the line you use for calculating the slope or use EXCEL to find the equation for the best fit line). - From the calculated slope, calculate the concentration of nitrite ion in the unknown solution - number of micrograms of NOx per liter of smoke - concentrations in ppm (see equation 12; p.54)Chem 20L Fall 2003 Report Guideline for Experiment 3 (Cigarette Experiment) Refer to laboratory syllabus for the due date of the post-lab report. Post-lab MUST be written inside your lab notebook (with the exception of graphs) (II) Post-lab Report Guideline (Continued) (D) Error Analysis for NOx Graph (MUST SHOW ALL WORK FOR FULL CREDIT) If there is no error listed on the bottle of the stock nitrite solution, you may assume the absolute error in the stock solution to be +/- 0.20 µg/mL. You may assume the absolute error for a 25-mL volumetric flask is +/- 0.02mL Absolute errors for all the other glassware are listed on p.31 of the lab manual. Refer to the lecture guide on error analysis for Beer's Law - error in concentration of standard solution (all terms identified and error bars placed on graph) - error in absorbance of standard solution (all terms identified and error bars placed on graph) - calculate the range of slopes of standard line. You MUST show mathematically how you obtain those slopes (i.e. max. slope and min. slope must be labeled clearly on your graph) - error in absorbance of the unknown NOx solution - absolute error range in concentration of the unknown NOx solution - estimate the % inherent error in the unknown NOx solution (Must identify each term in the error analysis) (E) Conclusions - summarize results - comment on % inherent error (i.e. is it reasonable for a Beer's law experiment?
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