Question 7 A student performed three DCM layer titrations in Part 2 and they reported the following measurements: Determination #1 Determination #2 Determination #3 Final Burette 31.12 mL 38.12 mL 45.00 mL Reading Initial Burette 24.21 mL 31.12 mL 38.12 mL Reading Volume of DCM 6.91 mL 7.00 mL 6.88 mL Aliquot Final Burette 31.52 mL 35.64 mL 44.99 mL Reading Initial Burette 2.43 mL 9.39 mL 19.31 mL Reading Volume of Sodium Thiosulfate 29.09 mL 26.25 mL 25.68 mL Which determinations were the student's 'best two'? Calculate the percent difference for the 'best two' and show the complete calculation. Note that the concentration of standard sodium thiosulfate, which the student used, is unknown. U RA Paragraph B I + v

Question 7 A student performed three DCM layer titrations in Part 2 and they reported the following measurements: Determination #1 Determination #2 Determination #3 Final Burette 31.12 mL 38.12 mL 45.00 mL Reading Initial Burette 24.21 mL 31.12 mL 38.12 mL Reading Volume of DCM 6.91 mL 7.00 mL 6.88 mL Aliquot Final Burette 31.52 mL 35.64 mL 44.99 mL Reading Initial Burette 2.43 mL 9.39 mL 19.31 mL Reading Volume of Sodium Thiosulfate 29.09 mL 26.25 mL 25.68 mL Which determinations were the student's 'best two'? Calculate the percent difference for the 'best two' and show the complete calculation. Note that the concentration of standard sodium thiosulfate, which the student used, is unknown. U RA Paragraph B I + v

Appl Of Ms Excel In Analytical Chemistry

2nd Edition

ISBN:9781285686691

Author:Crouch

Publisher:Crouch

Chapter12: Spectrochemical Methods

Section: Chapter Questions

Problem 15P

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6. The mass percent of KHP in an unknown salt sample was determined using both volumetric and gravimetric titration. Ten determinations using each method were performed: (You should be using Excel to solve for the required values) Volumetric (% KHP): 34.22 33.86 34.07 34.49 34.69 33.71 34.28 34.11 34.26 34.10Gravimetric (% KHP): 34.35 34.26 34.10 34.19 34.18 34.32 34.11 34.33 34.17 34.12 a) Do the two methods give similar standard deviations? b) Do the two methods give similar results for the mass percent of KHP at the 95% confidence level?
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Part A: Standardization of a Sodium Hydroxide Solution Titration 1 Titration 2 Titration 3 Mass of 125 mL flask 45.849g 46.715g 44.953g Mass of flask and KHP 46.849g 47.745g 46.003g Initial buret reading (mL) 0.5 ml 0.5 ml 0.5 ml Final buret reading (mL) 27.8 ml 26.5 ml 26.7 ml Volume of NaOH used (mL) 45.11 ml 45.06 ml 45.14 ml Calculations Titration 1 Titration 2 Titration 3 Moles of KHP Moles of NaOH Molarity of NaOH Average Molarity of NaOH: _______________
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