Comments about the Iodine Clock Experiment:

I checked out Ludy's and Jeff's lab sections Tuesday morning. Basically their student's data looked fine. Data point #1 (10 mLs of S₂O₃^2-) is around 60 seconds and data point #2 (10 mLs of S₂O₃^2-) is about half that. For data point #3 students used a variety of volumes of thiosulfate. In the two labs this morning I saw 3 mLs, 7 mLs, 1 mL and 2mLs. The times which appeared reasonable were;

Volume of S2O32-	time
7 mLs	40 s
3 mLs	18 s
2 mLs	10 s
1 mL	5 s

I want six data points plotted when determining the order of the reaction with respect to S₂O₈^2-. Students are to use their three data points (Experiments #1, 2 and 3) and then three additional data points from the table above. If one of the data points in the table correspond to the volume used in Experiment #3 students are to use their time measurement NOT the one in the table. For the remaining three data points use the volumes and times provided in the table. The additional data will demonstrate a better line for their plot.

If you are concerned about your data or are missing any data talk to your TA during laboratory.

When determining the order of the reaction with respect to S₂O₈^2- do not [S₂O₈^2- ]^-1 versus time. Just plot ln[S₂O₈^2- ] versus time.

(When I plotted those six data points (10, 5, 7, 3, 2 and 1) I get a pretty nice straight line for both ln[] versus time AND 1/[] versus time. Clearly we need more data beyond the range we are viewing to see the curve. Although I thought I could see a bit of a curve in the 1/[] vs time plot. However, it will be difficult for the students to discern that curve. My suggestion is to tell the students NOT to plot 1/[] versus time (as requested in the new and improved laboratory write-up). )

For determining the order of the reaction with respect to iodine do all combinations of data pairs to get the order. That is, do 1&4, 1&5 and 4&5.

Is all this clear? Drop by and see me if you have questions.

Here is the new and improved version of the data analysis section of the Iodine Clock Experiment. Copies will be available in laboratory.

Here is this Iodine Clock laboratory. Be sure to answer the questions on the first two pages before arriving to discussion next week.

Week I and II:

Laboratory the first two weeks will be busy dealing with administrative details, safety videotape and quiz, a CHEM1314/CHEM1515 Introductory Survey and the Review Problem Set. You are also encouraged to ask your TA questions on Problem Set #1 and #2. Depending on how things are going by the second week we may begin Experiment #1 on Survival Organic Chemistry. We'll see.

Most important is to bring your calculator and textbook to laboratory these first three to four weeks. There is material in the textbook which you will want to have access to during the laboratory.

Week III:

Laboratory #1: Survival Organic Chemistry

This first experiment will provide you an opportunity to learn more about the three dimensional structure of simple organic compounds, organic nomenclature and isomerism in organic compounds. If you need a copy get it here. Below are some WEB sites which may be of use to you as you prepare and learn this material.

• www.colby.edu/chemistry/webmo/mointro.html

  This particular site contains a large collection of simple inorganic and organic structures. The only problem is the need to have a particular plug-in inorder that your browser display the structures in a window and allow the user to manipulate the image (rotate/scale/etc). If you go to the plug-ins page you can get the MDL ChemScape Chime which will allow you to view and manipulate these structures.

• oksw01.okanagan.bc.ca/chem/nomenclature/index.htm

This site has information on naming hydrocarbons. It also has information about isomers. If you have the MDL ChemScape Chime there are .pdb files which can be viewed and manipulated.