CHEM 142 Lab 3 Report
CHEM 142 Lab 3 Report CHEM 142
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This 5 page Class Notes was uploaded by Angel Lee on Saturday October 31, 2015. The Class Notes belongs to CHEM 142 at University of Washington taught by David Ginger in Fall 2015. Since its upload, it has received 870 views. For similar materials see General Chemistry in Chemistry at University of Washington.
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Date Created: 10/31/15
Name Section ID Number Lab Partner Chem 142 Experiment 3 Calibration Curves and an Application of Beer39s Law By signing below you certify that you have not falsified data that you have not plagiarized any part of this lab N t report and that all calculations and responses other than the reporting of raw data are your own independent 0 e39 work Failure to sign this declaration will result in 5 points being deducted from your report score All sections Of 8 I this report must ignature be typed Total Points 55 pts 10 pts notebook 45 pts template DATA GRAPHS AND CALCULATIONS Creating the calibration curve Ferroin Concentration M Absorbance 2 pt 125E05 0094 250E05 0180 375E05 0305 500E05 0406 625E05 0517 Absorbance vs Concentration of Ferroin M 0600 0 500 y 8576x 00212 39 R2 09977 4 pts 0400 8 58 5 0300 8 Q lt 0200 0100 0000 000500 100E05 200E05 300E05 400E05 500E05 600E05 700E05 Concentration of Ferroin M Slope of Absorbance versus concentration graph 2 pts 8576 M391 yintercept of Absorbance versus concentration graph 0021 Detailed calibration equation absorbance 8576 Mquot1 ferroin 00212 2 pts review the introductory information in the lab manual for an explanation of what is meant by a quotdetailedquot calibration equation Determining the Amount of Iron in an Iron Tablet 3 pts 1 Average mass of a tablet 436 mg 2 Mass of crushed tablet used in analysis 22 mg 3 Final volume after filtered crushed tablet solution I 100 mL is diluted in volumetric flask lab manual Part II Step 5 4 Volume of diluted crushed tablet solution I 5 mL transferred to the new volumetric flask lab manual Part II Step 6 5 Final volume of ferroin complex solution I 100 mL lab manual Part II Step 9 6 Absorbance of the ferroin complex solution I 0077 lab manual Part III Step 3 7 Usin the calibration equation and the absorbance you measured for the prepared sample calcu ate the ferrom concentration Show your work and don39t forget to Include units 0077absorbance 8576absorbanceconcentrationx 00212absorbance 00982 absorbance 8576absorbanceconcentrationx 3 pts x 11 10quot5 concentration of ferroin M 8 Based on the procedural steps and the ferroin concentration you just calculated calculate the moles of ferroin in the final ferroin complex solution prepared in Part II Step 9 Show your work including units 11 10quot5 concentration of ferroin M 100 mL 11 10quot5 mol of ferroinL 01 L 3 pts 1 10A6 mol of ferroin 9 Based on the moles of ferroin in the final ferroin complex solution calculate the moles of iron in the crushed tablet solution prepared in Part II Steps 25 Show your work including units 1 10A6 mol of ferroin 100 mL of diluted crushed tablet solution 5 mL of diluted crushed tablet solution 3 pts 2 10quot5 mol of ferroin in crushed tablet solution 1 mol of iron 1 mol of ferroin 2 10quot5 mol of iron in crushed tablet solution 10 Using the quotmoles of iron in the crushed tablet solutionquot you just calculated calculate the mass in mg of iron in the crushed sample that you weighed out Show your work including units 2 10quot5 mol of iron in crushed tablet solution 5585 g of iron 1 mol of iron 3 pts 1 10quot3 grams of iron in crushed tablet solution 11 From the mass of iron in the crushed tablet sample you weighed out calculate the mass in mg of iron in a whole tablet Show your work including units 1 10quot3 g of iron in crushed tablet 436 mg per tablet 1 10quot3 g of iron in crushed tablet 0436 g per tablet 22 mg of crushed tablet 0022 g of crushed tablet 3 pts 6 10 quot 2 grams of iron 0436 g 3 10quot2 grams of iron per tablet 30 mg of iron per tablet 1 g of crushed tablet 12 mg of iron per tablet as listed on the bottle I 27 mg Results and Discussion 1 Compare your mass of iron per tablet with the amount listed on the bottle label Calculate the error and discuss YOUR major sources of error 4 pts 30 27j 100 11 11 error My result has a percent error of 1111 percent 1 conjecture major sources of error were probably 27 derived from errors in measuring the volumes of water that was added to dilute the solution According to the lab manual the steps in diluting a solution said to roughly estimate the amount of water added to the solution This rough estimate could have affected the final results In addition to these errors there could have been errors in reading the balance while measuring the mass of the crushed tablet 2 If you did not wait for the complete formation of the ferroin complex in Part 11 step 10 how would your Abs data be different Explain how would this affect your determination of the mass of iron in the tablet 4 pts If I had not waited for the complete formation of the ferroin complex the absorbance of the ferroin solution could have been much lower With a lower absorbance I would have attained a lower ferroin concentration from my calculations because concentration and absorbance are positively proportional Therefore a smaller number of moles of ferroin could have also resulted These values which were used to find the moles of iron in my crushed tablet solution could have given a me a smaller mass of iron in the tablet 3 You use atomic emission spectroscopy another spectroscopic technique to measure the Li concentration in 5 standard solutions of varying concentrations of LiCl The intensities for the standard solutions are plotted versus the concentrations and the resulting calibration equation is Intensity 83100 M391 Li 165 If the intensity of your unknown sample is 101 what is the concentration of Li in the analyzed sample 4 pts 101 83100 M391Li165 9935 83100 Mquot1 Li Li 120 10quot3 M H 15 mL of the original unknown sample was diluted to 350 mL prior to analysis what is the concentration of Li in the original solution 4 pts 120 10quot3 M 350 mL 120 1043 molL 0350 L 42 1044 molLi 42 10 4 mol Li 42 10 4 mol Li 28 10A2 M 15 mL 0015 L Laboratory Waste Evaluation 1 pt Laboratory waste is considered anything generated during an experiment that is disposed of down the sewer drain thrown in the garbage collected in a container for disposal by the UW Environmental Health amp Safety department or released into the environment Based on the written lab procedure and your actions during the lab list the identity and approximate amount mass or volume of waste that you generated while performing this experiment 5 mL ferroin stock solution 22 mg of iron tablet powder 2 mL of 01 M HCI 100 mL of water 2 mL of 023 M hydroxylamine hydrochloride 1 mL of 10 M sodium acetate solution 3 mL of 36 10 A3 1 10 phenanthroline 89 mL of water 2 disposable pipets
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