Chem142_Calib_Report_Gradescope_021819_PC

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Name: Monserrat Diaz Quiz Section AC Lab Partner: Mia Elsberry Student ID #: 2229660 CHEM 142 Experiment #4: Calibration Curves and an Application of Beer's Law Goals of this lab: • Apply the use of a calibration curve to finding the concentration of an unknown • Apply the mechanics of dimensional analysis to calculate the mass of iron in a sample based on concentration of an iron-containing solution • Develop lab skills in operating digital pipettes, volumetric glassware, and spectrophotometers • Use Excel to graphically represent and interpret experimental data • Asses the accuracy of experimental data (compared to a known value) and identify sources of error Your lab report will be grade on the following criteria using a poor/good/excellent rating system (see the Lab 4 Self-Assessment for more details): • Calculations are complete and correct, with proper use of significant figures and units • Data and results are careful and accurate • Lab report is clear, legible, and neat • Error analysis is well-supported and valid • All graphs and tables and clearly and accurately labeled; entire report is typed • Application of skills to new situations is accurate and complete By signing below, you certify that you have not falsified data, that you have not plagiarized any part of this lab report, and that all calculations and responses other than the reporting of raw data are your own independent work. Failure to sign this declaration will result in 5 points being deducted from your lab score. Signature: __Monserrat Diaz______________________________________ This lab is worth 60 points: 10 points for notebook pages, 50 points for the lab report

NAME: Monserrat Diaz QUIZ SECTION: AC DATA, GRAPHS AND CALCULATIONS Creating the calibration curve: l max for absorbance measurments: 513.7 nm (from Part III. B.) Ferroin Standards: Concentration (M) Absorbance (from Part III. C.) 1.25E-05 0.161 2.50E-05 0.360 3.75E-05 0.473 5.00E-05 0.608 6.25E-05 0.949 Slope of Absorbance versus concentration graph 14592 M -1 (enter #s here so the data y-intercept of Absorbance versus concentration graph will correctly autofill on pg 3) 0.037 Detailed calibration equation: (review the introductory information in the lab manual for an explanation of what is meant by a "detailed" calibration equation) Determining the Amount of Iron in an Iron Tablet 1) Average mass of a tablet 436 mg 2) Mass of crushed tablet used in analysis 60.0 mg (enter a # here so the data will correctly autofill on pg 3) 3) 100 mL is diluted in volumetric flask (lab manual Part II, Step 5) 4) Volume of diluted crushed tablet solution 5 mL transferred to the new volumetric flask (lab manual Part II, Step 6) 5) Final volume of ferroin complex solution 100 mL (lab manual Part II, Step 9) 6) Absorbance of the ferroin complex solution 0.450 (enter a # here so the data Final volume after filtered crushed tablet solution Abs=(14592 M^-1x[ferroin(M)])+0.037 Place your calibration plot here. enought for someone else to read. This calibration plot is Abs vs. concentration of ferroin (M) (y-axis vs. x-axis) Use the online resources if you need help figuring out how to plot a graph in Excel. Title the graph and label the axis, including the correct units (Absorbance data is unitless). Be sure to double check your units and formatting once you print the report. Add a Trendline to show the linear fit of your data. "display the equation on the chart", including the R Note: All sections of this report must be typed y = 14592x - 0.037 R² = 0.956 0.000 0.100 0.200 0.300 0.400 0.500 0.600 0.700 0.800 0.900 1.000 0.00E+00 1.00E-05 2.00E-05 3.00E-05 4.00E-05 5.00E-05 6.00E-05 7.00E-05 Absprbance Ferroin Concentration(M) Absorbance

(lab manual Part III, Step C.7) will correctly autofill on pg 3)

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NAME: QUIZ SECTION: Student- specific data from pg 2 used in calculations autofill here on this page: Calib. Curve slope: 14592 y-int of Calib. Curve: 0.037 Absorbance of digested sample: 0.450 Mass crushed tablet: 60.0 7) 8) 9) 10) 11) 12) mg of iron per tablet (as listed on the bottle) 27 mg Using the calibration equation and the absorbance you measured for the prepared sample, calculate the ferroin concentration. Show your work and don't forget to include units. Abs=(14592 M^-1 x [ferroin(M)])+ 0.037 0.450=(14592 M^-1 x [ferroin (M)])+ 0.037 0.450- 0.037=(14592 M^-1 x [ferroin (M)]) 0.450/14592 M^-1 = 3.08E-05 M ferroin 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. 3.08E-05 mol/L Ferroin x (100mL x 1L/1000mL)= 3.08E-06 moles ferrroin 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 2-5. Show your work, including units. 1 mole Ferroin = 1mole iron 3.08E-06 moles ferroin/ (5mL x 1L/1000mL)= 6.16E-04 M Ferroin in crushed tablet solution 6.16E-04 M ferroin in crushed tablet solution x (100mL x 1L/1000mL)= 6.16E-05 moles of iron in crushed tablet solution Using the "moles of iron in the crushed tablet solution" you just calculated, calculate the mass (in mg) of iron in the crushed sample that you weighed out. Show your work, including units. 6.16E-05 moles of iron in crushed tablet solution x 55.85 g/mol = 0.00344 g iron 0.00344g iron x (1000mg/ / 1g) = 3.44 mg iron 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. Mass of a whole iron tablet: 436 mg Mass of crushed tabet used in analysis = 60mg Mass of iron in the crushed sample: 3.44 mg 436mg/60mg= 7.3 7.3 x 3.44 mg iron = 25.1 mg iron in whole iron tablet 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. How did this affect your results? % error = (| actual value - expected value | / expected value ) x 100 % error = ( | 25.1 mg - 27mg | /27mg) x 100 % error = 7.0% error One major = One major source of error was our solution didn't fully dissolve. We could see bits and pieces of the iron that were left over. we spinned and boiled it for a while longer and still it did not dissolve. They contirbuted to the mass of our iron sample, although they were no longer iron after the boliing they caused us to have a decreas in the amount of mg of iron from our

NAME: QUIZ SECTION: 2. If you did not wait for the complete formation of the ferroin complex in Part II, step 10, how would your Abs data be different? Explain how would this affect your determination of the mass of iron in the tablet? If you don't wait for the complete formation of ferroin solution , then the abosrbance measuremnets would have been affected because less iron is being reacted. Making it hard to find the mass of iron in the tablet because it doesnt have the proper absorbance. 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 = 82,985 M -1 * [Li + ] + 2.15 If the intensity of your unknown sample is 132, what is the concentration of Li + in the analyzed sample? Concerntration of Li^+ = (132 - 2.15) / 82,985 = 0.00156 M If 15 mL of the original unknown sample was diluted to 375 mL prior to analysis, what is the concentration of Li + in the original solution? Mole of Li^+ = (0.00156 M) x (0.375 L) = 0.000585 mol Concentration. of L^+ = (0.000585 mol) / (0.015 L) =0.0391 M Laboratory Waste Evaluation 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 & 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. -1/2 liter waste bottle -32 ounces of DI water -paper towel -1 plastic pipet -1digital pipette tip -2mL hyrdroxylamine hyrdrochlorid -1mL sodium acetate -5mL phenanthroline although they were no longer iron after the boliing they caused us to have a decreas in the amount of mg of iron from our tablet. Another major source was time, havingt o wiat between the trials and solutions to properly mix as well as making sure i was worling efficiently.