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Unformatted text preview: Experiment 14 Determination of an Equilibrium Constant Spring 2010 Name Chelsea McMullen Lab Section 428 Point Summary (See Blackboard for detailed grading rubric) Superior Excellent Satisfactory Fair Poor Omitted Introduction Purpose of Report 4 Goals of Experiment 4 Materials and Methods 2 Results and Discussion Description of data 4 Data Tables 5 Data Table Titles 4 Graphs 5 Figure Captions 4 Sample Calculations 2 Systematic Error 6 Random Error 6 Discussion of discrepancies 6 Other 8 Lab Technique 15 TOTAL POINTS 75 TA Comments/Suggestions: Need semester you are taking the lab for complete reference to the lab manual. Too many sig figs in sample calculations. Should be limited to 2 by initial mass measurement. Error discussion needs to be more quantitative. Show numbers. C HEMISTRY 102L R EPORT T EMPLATE EXPT. Determination of an Equilibrium Constant 14 14 Introduction The purpose of this report is to determine the equilibrium constant of five equilibrium solutions of FeSCN 2+ by using the absorbance of each solution. The objective of this experiment was to determine the concentrations of various equilibrium solutions of FeSCN 2+ by using Beers Law and the known absorbance of each solution, found using a colorimeter, and from the determined concentrations, then find the concentrations of both Fe 3+ and SCN- in all the solutions. Once these concentrations were found, the equilibrium constant could then be determined. Materials and Methods The procedure for this experiment was taken from the UNC Chemistry 102L Lab Manual Experiment 14: Determination of an Equilibrium Constant in Aqueous Solution. There were no deviations from the procedure. Results and Discussion The stock solutions were prepared according to the chart that was provided in the lab manual. In order to find the concentration of each stock solution, the moles of the solid substance, either Fe(NO 3 )9H 2 O or NaSCN, was found, and then divided by the volume of solution to find the molarity of each solution. The absorbance of each solution was found using a colorimeter....
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