Chemistry 105 Lab Schedule -- Spring 2010 -- TuTh Morning -- D. Zellmer

 

Text: Skoog, West, Holler and Crouch, Analytical Chemistry--An Introduction, 7th Edition.

 

1 per. 1.   Safety and Balance Instruction. Also read SWHC Ch. 2, pp. 21-60, Lab Procedures. Each student will weigh the same object on all 10 electronic balances and will post the results.
Begin Th 21 Jan-- End Th 21 Jan 2010

 

4 per. 2.   Check In and Gravimetric Determination of Chloride -- Solid Unknown (also used for Vol Cl below)
Procedure as in SWHC 27B-1, pp. 728-730 except assume unknowns are 60% by weight of chloride and digest precipitate unheated until the next period. Glassware calibration (below) is done while you wait. Prepare 500 ml of 0.1M Silver Nitrate, not 0.2 M. Use the remainder for Volumetric Chloride. Report %Cl.
Begin Tu Jan 26-- End Tu 9 Feb (5 periods -- includes glassware calibration. below)

 

1 per. 3.   Calibrate Volumetric Glassware (SWHC 27A-4 pages 725-726). Do 10 ml pipet, and 25 ml pipet. Using the same technique, calibrate your buret at 20 mL, 30 mL, and 40 mL. Compare volume as read with volume computed from mass. Report results in laboratory notebook.
--done during the AgCl digestion period.

 

3 per. 4.   Volumetric Determination of Chloride Using Adsorption Indicator. Same Solid Unknown used above for Grav Cl. SWHC 27-D2 page 741. Report %Cl.
Begin Th 11 Feb -- End Th 18 Feb. Results of %Cl Grav and Vol due Tue 23 Feb.

 

4 per. 5.   Determination of %KHP in a solid unknown. Procedure as in SWHC 27-C4, 27C-7, and 27C-8 (note that 27C-9 shows a relevant application to food science) pp. 733-736; except prepare standard KHP solution (12 millimoles in 100 ml) and do standardization with aliquots. Evaluate two indicators (methyl red and phenolphthalien) by doing a titration curve of some KHP with a pH meter. A critical evaluation of the endpoints will be required (25 points)(see handout) in addition to the usual unknown results. Report %KHP (100 points, as usual).
Begin Tu 23 Feb-- End Th 4 Mar. %KHP results due Tue 9 Mar. Endpoint Evaluation Report due Tu 16 Mar.

 

4 per. 6.   Determination of Calcium with EDTA. Solid Unknown. Procedure on handout. (See also SWHC 27E pp. 741-743) Report %CaO.
Begin Tu 9 Mar-- End Th 18 Mar. %CaO results due Tue 23 Mar.

 

5 per. 7.   Spectrophotometric Iron. Solid Unknown. Procedure for molecular absorption in SWHC, 27L pages 764-765, except you will need to use the 50 ml volumetric flasks in your lockers and calculate your own dilutions. You will also need to prepare your own unknown solution by dissolving some of your Fe ore unknown as described in the Redox Titration experiment. Once standards and unknowns have been prepared for Molecular Absorption Spectrophotometry, we will have you make runs on Atomic Absorption as well. Your instructor will provide directions for AA. Report %Fe in the solid unknown by both methods (80 points Spec20+20 points AAS). Begin Tu 23 Mar-- End Tu 13 Apr. %Fe results by both methods due Tu 20 April.
Note: Spring Break is 29 Mar - 2 April.

 

4 per. 8.   Determination of Iron in Ore by Redox Titration. Use the same unknown issued for Experiment 7. Procedure SWHC 27F-1, p.744 (Prep of Permanganate); 27F2, p.744-5 (Stdz. of Permanganate); 27F-4, p. 747-749 (Determination. of Fe in ore.). Report %Fe in the ore.
Begin Th 15 Apr -- End Tu 27 Apr. %Fe results due Tu 4 May.

 

3 per. 9.   Determination of Ethanol by GLC. Liquid unknown, prepared by instructor. Procedure 27O, p. 772, except also add methanol as an internal standard. Report % Ethanol in your unknown (50 pts), and an independent spreadsheet report of your analysis (50 pts).
Begin Th 29 Apr -- End Th 6 May. Results and Report due Tu 11 May.

 

1 per. 10. Clean up and check out. No experiments on Tuesday, May 11, 2010 (last lab day is checkout only).

 

Laboratory results must be reported during the week following the last day of the experiment. Experiments finished but with unacceptable errors are worth 30 points. Experiments not completed are worth 0 points. A 20-point penalty is exacted for repeated or recalculated experiments, unacceptable precision, or for a new unknown to replace one you botched. Late penalties of 5 points per period may be assessed at the discretion of your instructor.