8:08 AM Wed Dec 18 Final Exam 2024 copy Home Insert Draw Page Layout Formulas Data Review AA 田 General A G fx Alexis Cozort ☑ ⚫ 61% A B D E F H K M N P R S T U 44 45 46 47 48 49 => (YES/NO) [H3O+] Let's test if we can do an approximation where, Ca / Kal > 50 Ca Kal we cannot apply the approximation. As you might predicted, solve the relations below: 50 = = 50 51 52 <= (*Define with variables) [H3O+] = = Και Kw )1/2 C Ka2 Cs = Ca numeral unit ) 1/2 53 (*Calculate with numerals) 54 55 Thus, isoionic pH is => pH = [H3O+] log [OH-] 56 (*Define) 57 => pH = numeral == 58 (*Calculate) 59 60 (ii)Calculate amino acid Cysteine's isoelectric pH? 61 62 pH = (pkal (Kal) 1/2 Ka2) pKa2) 63 (*Define) 64 65 => pH numeral = [H₂Cys*] [*HCys] [Cys-] 66 (*Calculate) 67 68 Bonus: The fraction of Cysteine [Cys-] form at pH = 9 is 69 numeral a(Cys-) = (% value or decimal is fine) 70 (iii-a)Click/drag the Arrow/s on the fractional composition plot in Figure-2, to prepare the best buffer from an acid & its conjugate salt base? 71 72 (iii-b) For a basic buffer, I picked the pH = because the concentrations of the form and the 73 74 form are The zwitter ionic form is the form, which is dominant in the pH window between 75 76 pH to pH = 77 78 79 80 81 3-(a)With reference to the plot of "Minimum pH for effective titration”, in the Appendix, Figure-3, I will prepare ferrous Fe²+-EDTA (*Click/drag the dotted red arrow to determine the pH) Numeric Answers + Page-1 Page-2 Appendix Fraction a "H,N' COOH "H,N' Coo H₂N Coo 1.0 FIGURE-2 complex 28 Zwitterionic form Both groups protonated 6 PH 10 Both groups deprotonated 8:07 AM Wed Dec 18 Final Exam 2024 copy Home Insert Draw Page Layout Formulas Data Review AA 田 General A G fx Alexis Cozort ☑ ⚫ 61% A B D E F H K M N P R S T U 3+ 10 125 mM that yielded peak heights of Aa = 9 1-(a)A sample solution was examined under XRF to quantify the analyte Ce³+. Find the response factor F, when standardized concentration of analyte [Ce³+]A = concentration of internal standard S i.e. [In³*]s = 151 mM was spiked with standardized 1600 and As = 3015 respectively? 11 12 (i)Define F, F = Aa As [A] [S] + X 13 (*Define with variables) 4000 14 15 (ii)Calculate F, F = numeral (You will use the F value in part 1-(b) below) As 16 (*Calculate with numerals) 17 18 1-(b)To determine the unknown conc of analyte [Ce³+], a volume of 15 mL of internal standard S having a concentration [In³+]s = 0.264 M 19 20 was added to 45 mL of unknown, and the mixture was diluted to 100 mL in a volumetric flask. XRF analysis yielded a spectrum, Figure-1, where peak heights A and As are determined from Intensity axis (Check yellow highlight below). Calculate unknown concentration (M) of the analyte [Ce³+]? Intensity (a.u.) 2000- Aa 21 numeral unit 22 Conc of diluted std., [In³]d=] = + 23 (*Calculate with numerals) 24 25 |=> Unknown concentration of diluted analyte, [Ce³+]d 0 10 20 Energy (keV) 30 FIGURE-1 26 27 (i)Define [Ce³+]d, [Ce³+]d = Aa As F [In³+]d + X 28 (*Define with variables) 29 numeral unit (*Click/drag the dotted red arrows to determine the Intensity of peak heights A) 30 (ii)Calculate [Ce³]d, [Ce³]d = 31 (*Calculate with numerals) 32 numeral unit 33 => Original concentration of the analyte, [Ce3+] = = From spectrum, I estimate Aa = As = 34 (*Calculate with numerals) 35 36 37 2-(i) Find the concentration of hydroniums [H3O+] hence evaluate the isoionic pH of the amino acid Cysteine solution having a molarity Ca= 0.22 M? pKa1 = 1.7 pKa2 10.8 38 numeral unit PM pH pKa1 39 <= Και = 10- 40 (*Define) (*Calculate) 41 numeral unit 42 => Ka2 = 43 AA Page-1 = (*Define) (*Calculate) Page-2 Appendix Numeric Answers + PM 10- pH pKa2

8:08 AM Wed Dec 18 Final Exam 2024 copy Home Insert Draw Page Layout Formulas Data Review AA 田 General A G fx Alexis Cozort ☑ ⚫ 61% A B D E F H K M N P R S T U 44 45 46 47 48 49 => (YES/NO) [H3O+] Let's test if we can do an approximation where, Ca / Kal > 50 Ca Kal we cannot apply the approximation. As you might predicted, solve the relations below: 50 = = 50 51 52 <= (Define with variables) [H3O+] = = Και Kw )1/2 C Ka2 Cs = Ca numeral unit ) 1/2 53 (Calculate with numerals) 54 55 Thus, isoionic pH is => pH = [H3O+] log [OH-] 56 (Define) 57 => pH = numeral == 58 (Calculate) 59 60 (ii)Calculate amino acid Cysteine's isoelectric pH? 61 62 pH = (pkal (Kal) 1/2 Ka2) pKa2) 63 (Define) 64 65 => pH numeral = [H₂Cys] [HCys] [Cys-] 66 (Calculate) 67 68 Bonus: The fraction of Cysteine [Cys-] form at pH = 9 is 69 numeral a(Cys-) = (% value or decimal is fine) 70 (iii-a)Click/drag the Arrow/s on the fractional composition plot in Figure-2, to prepare the best buffer from an acid & its conjugate salt base? 71 72 (iii-b) For a basic buffer, I picked the pH = because the concentrations of the form and the 73 74 form are The zwitter ionic form is the form, which is dominant in the pH window between 75 76 pH to pH = 77 78 79 80 81 3-(a)With reference to the plot of "Minimum pH for effective titration”, in the Appendix, Figure-3, I will prepare ferrous Fe²+-EDTA (Click/drag the dotted red arrow to determine the pH) Numeric Answers + Page-1 Page-2 Appendix Fraction a "H,N' COOH "H,N' Coo H₂N Coo 1.0 FIGURE-2 complex 28 Zwitterionic form Both groups protonated 6 PH 10 Both groups deprotonated 8:07 AM Wed Dec 18 Final Exam 2024 copy Home Insert Draw Page Layout Formulas Data Review AA 田 General A G fx Alexis Cozort ☑ ⚫ 61% A B D E F H K M N P R S T U 3+ 10 125 mM that yielded peak heights of Aa = 9 1-(a)A sample solution was examined under XRF to quantify the analyte Ce³+. Find the response factor F, when standardized concentration of analyte [Ce³+]A = concentration of internal standard S i.e. [In³]s = 151 mM was spiked with standardized 1600 and As = 3015 respectively? 11 12 (i)Define F, F = Aa As [A] [S] + X 13 (Define with variables) 4000 14 15 (ii)Calculate F, F = numeral (You will use the F value in part 1-(b) below) As 16 (Calculate with numerals) 17 18 1-(b)To determine the unknown conc of analyte [Ce³+], a volume of 15 mL of internal standard S having a concentration [In³+]s = 0.264 M 19 20 was added to 45 mL of unknown, and the mixture was diluted to 100 mL in a volumetric flask. XRF analysis yielded a spectrum, Figure-1, where peak heights A and As are determined from Intensity axis (Check yellow highlight below). Calculate unknown concentration (M) of the analyte [Ce³+]? Intensity (a.u.) 2000- Aa 21 numeral unit 22 Conc of diluted std., [In³]d=] = + 23 (Calculate with numerals) 24 25 |=> Unknown concentration of diluted analyte, [Ce³+]d 0 10 20 Energy (keV) 30 FIGURE-1 26 27 (i)Define [Ce³+]d, [Ce³+]d = Aa As F [In³+]d + X 28 (Define with variables) 29 numeral unit (Click/drag the dotted red arrows to determine the Intensity of peak heights A) 30 (ii)Calculate [Ce³]d, [Ce³]d = 31 (Calculate with numerals) 32 numeral unit 33 => Original concentration of the analyte, [Ce3+] = = From spectrum, I estimate Aa = As = 34 (Calculate with numerals) 35 36 37 2-(i) Find the concentration of hydroniums [H3O+] hence evaluate the isoionic pH of the amino acid Cysteine solution having a molarity Ca= 0.22 M? pKa1 = 1.7 pKa2 10.8 38 numeral unit PM pH pKa1 39 <= Και = 10- 40 (Define) (Calculate) 41 numeral unit 42 => Ka2 = 43 AA Page-1 = (Define) (*Calculate) Page-2 Appendix Numeric Answers + PM 10- pH pKa2

Principles of Instrumental Analysis

7th Edition

ISBN:9781305577213

Author:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Publisher:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Chapter9: Atomic Absorption And Atomic Fluorescence Spectrometry

Section: Chapter Questions

Problem 9.22QAP: The chromium in an aqueous sample was determined by pipetting 10.0 ml. of the unknown into each of...

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