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Unformatted text preview: Chem 14CL 8 - The Determination of the Concentration and Acid Dissociation Constants of an Amino Acid Summer 08 Pre-lab and Post-lab reports MUST be written inside your lab notebook. Refer to the lab schedule for due dates of both the post-lab and the pre-lab. Type written reports will NOT be accepted (with the exception of graphs). On line Technique and 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) Solution Preparation (3) 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 Chemical Hazard Symbols On-line resource for acid-base chemistry IMPORTANT: You should review the concepts of acid-base chemistry from 14A, 14BL and from the on-line tutorials listed here for this experiment. Chem 14CL 8 - The Determination of the Concentration and Acid Dissociation Constants of an Amino Acid Summer 08 Pre-lab Report Guidelines For Lab Period #1
Pre-lab report is due at the beginning of the lab section. Pre-lab report MUST be written inside your LAB NOTEBOOK. This experiment consists of THREE separate pre-lab reports. Due date for each part of the report is listed on this guideline. Lab period 1 pre-lab report is due on Wednesday 8/6
(I) Introduction - write down the goal(s) of the ENTIRE experiment as well as the experimental techniques that you will be using in order to achieve such goal(s). Construct flowchart of procedures for ONLY the following parts of the experiment Preparation of the Standard TRIS Solution (Primary Standard) Standardization of the HCl Solution (Secondary Standard) Standardization of the NaOH Solution (Secondary Standard) (Refer to the MSDS handout for more information) (II) (III) MSDS Information The following chemicals will require you to use the MSDS database on the Web: NaOH (0.1M to 0.2M); HCl (0.1M to 0.2M) and TRIS (0.1M to 0.2M)
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. For TRIS, you may have to use the complete IUPAC name for the search engine when using MSDS. Refer to the lab manual for the complete IUPAC name of TRIS. 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) (b) (c) (d) (e) (f) Product Name Chemical Formula Formula Weight Melting Point; Boiling Point and Density Health Hazard Data (summarize in your own words) Spill and Disposal procedures (summarize in your own words (IV) Set up blank data tables (Start a NEW page for this part) Note: Only set up blank data tables for the 3 parts of the experiment that outlined in (II) Chem 14CL 8 - The Determination of the Concentration and Acid Dissociation Constants of an Amino Acid Summer 08 Pre-lab is due at the beginning of the lab section. Pre-lab report MUST be written inside your LAB NOTEBOOK. Pre-lab Report Guidelines For Lab Period #2 Lab period 2 pre-lab report is due on Thursday 8/7
(I) (II) Construct flowchart of procedures for ONLY the following parts of the experiment Titration Analysis of the Unknown Amino Acid with HCl (refer to page 97) Titration Analysis of the Unknown Amino Acid with NaOH (refer to page 97) Study Questions Complete questions 1,2, &3 under "PERIOD 1" (Refer to pages 94 & 95) You MUST show all the calculations and work in order to receive full credit. Read pages 90-94 BEFORE attempting to complete the study questions. NOTE: Question 3 (see page 94) should read 3.29 ml of HCl and 18.61 ml of NaOH. For the HCl, you may assume that the 3.29mL corresponds to the first inflection point volume. The pKa's for the amino acid in question #4 can be determined based on the information given in question #3.
Hint: For question #3, assume that the 10-ml of unknown solution contains both the A & A- forms of the amino acid. Refer to the lab manual for the structures of the A, and A- forms of the amino acid. Pre-lab Report Guidelines For Lab Period #3 Lab Period 3 Prelab is DUE on Friday 8/8
Complete study question 1b ONLY under the section "Period 2" (Refer to page 95). Hint: Sketch the titration graph by calculating the pH at the following points on the titration graph. 0 mL, 5 mL, 10 mL, 15 mL, 20 mL, 25 mL, 30 mL & 40 mL of HCl You MUST show all work for full credit) NOTE THAT ALL pK IN THE PROBLEMS ARE pKa and not pKb ...
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- Summer '08