Chem 20L Winter 2005(II) Pre-lab Report GuidelineChem 20L Winter 2005Post-lab MUST be written inside your lab notebookPost-lab Report - This is a GROUP reportPost-lab MUST be written inside your lab notebookPost-lab Report - This is a GROUP report (Continued)Chem 20L Winter 2005 Report Guidelines for Assignment 4 (Titrations and Indicators) Pre-lab work is due at the beginning of the lab section. Refer to the laboratory syllabus for the due dates of the post-lab report. Pre-lab and post-lab reports MUST be written inside your lab notebook (with the exception of graphs.) The REVISED PROCEDURE for this experiment is supplemented as a handout. Make sure you read the revised procedure before writing your reports. (I) On-line Technique Videos & Resources For This Experiment Click on the title below to download the video (require Real Player) (1) Laboratory Safety (this video was shown on the first day of the lab) (2) Use of a Buret If you have trouble downloading the videos, go to the following Web site and click on the appropriate title to download the video. http://oid.ucla.edu/Webcast/Chemistry/ Guides for Writing Lab Reports Theory on pH Meter Theory of Acid-Base Indicators Various concentration units (including Normality and Molarity) (II) Pre-lab Report Guideline (I) Introduction (II) Procedure in Flowchart Format (use the REVISED PROCEDURES) (III) 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.) Include any changes to the procedure that you know you will make.Chem 20L Winter 2005 Report Guidelines for Assignment 4 (Titrations and Indicators) (II) Pre-lab Report Guideline (Continued) (IV) MSDS information (refer to the MSDS handout for details) The following chemicals will require you to use the MSDS database on the Web: Sulfuric Acid (0.2N or 0.1M) Note: In MSDS, select the site that gives you the MSDS information closest to the concentration listed above for each individual chemical. You may have to convert the concentration units on MSDS before you decide which site to use since sometimes the unit may be reported as w/v% in MSDS. 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) (V) Complete study questions #1 & #2 (see bottom of page 58 & 59): Show ALL your work and reasoning. Read pages 56-58 BEFORE you start working on the study questions. NOTE: For question 2(b), you may assume that BOTH protons dissociate completely. Useful mathematical relationship for pH and pOH: pH = -log[H+] and pOH = -log[OH-]. pH + pOH =14. (VI) Set up BLANK data table READ the procedure and set up the necessary data tables for the experiment. Note: Start a NEW page in your notebook for this section. The previous material will be turned in at the beginning of the period; this page will be turned in at the end of the lab periodChem 20L Winter 2005 Report Guideline for Assignment 4 (Titrations and Indicators) Post-lab MUST be written inside your lab notebook Post-lab Report - This is a GROUP report (I) Data, Observations and Responsibility If you are working with another student for this experiment, write the name of each of the group members for this experiment. Write out the responsibility of each group member when writing this report and during the experiment (i) Organize your data for EACH of the indicators in a table format (i.e. recopy the data that your group collected during the lab period into your post-lab report). For each table for an indicator, set up the following three columns: pH, buret volume (or volume of titrant added), color of the solution (II) Data Analysis & Discussions (ii) Calculate the normality (normal concentration) of the sulfuric acid for EACH indicator at the end point of the titration. Show ALL your work and reasoning. Note: At the equivalence point, the number of equivalents of acid equal the number of equivalents of base (please also read the example on page 57 of the manual): NA X VA = NB X VB where A stands for acid and B stands for base. NA = Concentration of the acid in normality; NB = Concentration of the base in normality VA = Volume of the acid required to titrate to the end point NB = Volume of base use in titration (iii) Assuming that the correct indicator for this experiment is bromocresol green, calculate the % deviation (or % difference) for the concentration of the sulfuric acid for the other two indicators. Show ALL your work. Note: % deviation is NOT the same as % RAD or % RSD.Chem 20L Winter 2005 Report Guideline for Assignment 4 (Titrations and Indicators) Post-lab MUST be written inside your lab notebook Post-lab Report - This is a GROUP report (Continued) (III) Error Analysis (iv) Calculate the % inherent error in the concentration of sulfuric acid for EACH of the indicator that you calculated in (ii). Show all your work. Assume that EACH indicator has an absolute error of ±0.05mL. Hint: Your post-lab report #2 will be a good source of reference on how to compute inherent errors. (v) What can you conclude about the % inherent error in relation to the choice of the indicators? (IV) Conclusion (vi) Summarize the normality of the sulfuric acid based on the end point volume for EACH indicator. (vii) Summarize the %deviation for the concentration in sulfuric acid for two of the indicators (viii) Explain the physical meanings of end point and equivalence point. (ix) What are the criteria for choosing an indicator for a titration experiment?
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