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I need help to produce a standard curve with the attached worksheet. The curve/graph should be absorbance versus concentration.

I need help to produce a standard curve with the attached worksheet. The curve/graph should be absorbance versus concentration.

Chemistry
Chemistry
10th Edition
ISBN:9781305957404
Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Chapter1: Chemical Foundations
Section: Chapter Questions
Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...
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I need help to produce a standard curve with the attached worksheet. The curve/graph should be absorbance versus concentration.
FuneuEpose of this exercise is to familiarize or refresh students on the execution and Eunction of ultraviolet/visible (UV/vis) light absorption spectroscopy. Toward that end the CeenES will determine and record the absorption values of a set of 4 standards and use the collected data t o determine the concentration of an unknown. Familiarize yourself with the Cundamentals of UV/vis absorption spectroscopy using at least your analytical chemistry (quantitative chemistry) text. I. Background Information The substance used in this lab is bromocresol green (BCG; you can look up the IUPAC name). turns green in an environment with a pH less than 3.8 and blue in an environment with between 3.8 and 5.4). The compound is a pH indicator which a pH greater than 5.4 (obviously blue-green The hydroxyl hydrogens are lost at high pH. Br BCG has wavelength (a) of about 450nm. diluting 0.0247g of BCG (s) to 100ml, with ddH,0 (distilled, deionized water) and a drop of 0.5M NAOH (aq) a molar mass of 698.02g/mol and a maximum absorption Stock solution of BCG is made by (for the deep blue color). Six tubes should be produced as follows: a. Blank (8000pL ddH,0) 2 b. Standard 1 (7500ui ddH,0 with 500pL stock BCG) TU bR 20 A c. Standard 2 (7000uL ddH.0 with 1000uL stock BCG) 4ube DP y d. Standard 3 (6500uL ddH,0 with 1500uL stock BCG) be 35° e. Standard 4 (6000pL ddH 0 with 2000pL stock BCG) be ho00 f. Unknown (8000µL unknown) II. Procedure Turn the spectrophotometer on at least 15 minutes ahead of time. a reflection of the needle on the dial then turn the front left knob to set needle to 0% transmittance. needle on the dial to 100% transmittance. first standard tube in the set; read and record the % transmittance. standard then do the same with the unknown. using A = 2 - log (&T); where A is absorbance, Line up so you don't see Place the blank into the sample cell. Turn the right front dial to set the Replace the blank in the sample cell with the Repeat with each Convert the % transmittance values to absorbance Record the absorbance values in III below. III. Data absorbance versus the concentration of each standard on graph paper. fit line will be e Plot (using appropriate scaling, with titles, axis labels, and units where applicable) the The slope of the best- extinction in A = ebc (Beer's where A is absorbance, coefficient, b the path length, and c the concentration of the sample). Law, the The value of bis typically 1, so it can be ignored. 1. Report the concentration of the stock BCG solution 353. 2. Report the concentration of each standard tube of BCG solution. 88.5 b. Tube 2 H-.2.M c. Tube 3 (ple4 uM uM a. Tube 1 22. µM d. Tube 4 3. Report the absorbance of each standard tube of BCG solution. 0.20 a. Tube 9 O.034 b. Tube Tube 3 O. 7 d. Tube 4 Report the absorbance of the unknown BCG solution. tube 4. Absorbance O.013 Curve 5. Produce and submit the standard curve along with this worksheet.( Make albr i bance 6. Report e for BCG and the concentration of the unknown BCG solution, 5.5 Concenti @tion Concentration Extinction Coefficient of BCG O.0024
Transcribed Image Text:FuneuEpose of this exercise is to familiarize or refresh students on the execution and Eunction of ultraviolet/visible (UV/vis) light absorption spectroscopy. Toward that end the CeenES will determine and record the absorption values of a set of 4 standards and use the collected data t o determine the concentration of an unknown. Familiarize yourself with the Cundamentals of UV/vis absorption spectroscopy using at least your analytical chemistry (quantitative chemistry) text. I. Background Information The substance used in this lab is bromocresol green (BCG; you can look up the IUPAC name). turns green in an environment with a pH less than 3.8 and blue in an environment with between 3.8 and 5.4). The compound is a pH indicator which a pH greater than 5.4 (obviously blue-green The hydroxyl hydrogens are lost at high pH. Br BCG has wavelength (a) of about 450nm. diluting 0.0247g of BCG (s) to 100ml, with ddH,0 (distilled, deionized water) and a drop of 0.5M NAOH (aq) a molar mass of 698.02g/mol and a maximum absorption Stock solution of BCG is made by (for the deep blue color). Six tubes should be produced as follows: a. Blank (8000pL ddH,0) 2 b. Standard 1 (7500ui ddH,0 with 500pL stock BCG) TU bR 20 A c. Standard 2 (7000uL ddH.0 with 1000uL stock BCG) 4ube DP y d. Standard 3 (6500uL ddH,0 with 1500uL stock BCG) be 35° e. Standard 4 (6000pL ddH 0 with 2000pL stock BCG) be ho00 f. Unknown (8000µL unknown) II. Procedure Turn the spectrophotometer on at least 15 minutes ahead of time. a reflection of the needle on the dial then turn the front left knob to set needle to 0% transmittance. needle on the dial to 100% transmittance. first standard tube in the set; read and record the % transmittance. standard then do the same with the unknown. using A = 2 - log (&T); where A is absorbance, Line up so you don't see Place the blank into the sample cell. Turn the right front dial to set the Replace the blank in the sample cell with the Repeat with each Convert the % transmittance values to absorbance Record the absorbance values in III below. III. Data absorbance versus the concentration of each standard on graph paper. fit line will be e Plot (using appropriate scaling, with titles, axis labels, and units where applicable) the The slope of the best- extinction in A = ebc (Beer's where A is absorbance, coefficient, b the path length, and c the concentration of the sample). Law, the The value of bis typically 1, so it can be ignored. 1. Report the concentration of the stock BCG solution 353. 2. Report the concentration of each standard tube of BCG solution. 88.5 b. Tube 2 H-.2.M c. Tube 3 (ple4 uM uM a. Tube 1 22. µM d. Tube 4 3. Report the absorbance of each standard tube of BCG solution. 0.20 a. Tube 9 O.034 b. Tube Tube 3 O. 7 d. Tube 4 Report the absorbance of the unknown BCG solution. tube 4. Absorbance O.013 Curve 5. Produce and submit the standard curve along with this worksheet.( Make albr i bance 6. Report e for BCG and the concentration of the unknown BCG solution, 5.5 Concenti @tion Concentration Extinction Coefficient of BCG O.0024
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