Flask123Flask123initial burettereading50 mL.38 mL28 mLvolume EDTArequired to chelate Ca²+final burettereading38 ml.28 mL20 mLtotal volumeVEDTAVuk...5........5................moles EDTAAverage moles of Ca2+/L-water =Average grams of Ca2+/L-water =1 mg/L = 1ppmAverage Hardness of water =moles Ca2+ presentin 25 mL water sample#7Volume EDTA requiredto chelate all Camoles Ca presentin IL water sample...molesgrams.....ppm Average [EDTA] =C: Determination of the hardness of an unknown water sample:Using an unknown water sample, three 25 mL samples in 3 separate 250 mL Erlenmeyer flasksare prepared. To each flask, 5 mL of pH pH10 buffer, 3 to 5 drops of Eriochrome Black Tindicator, and 15 drops of 0.03 M MgCl2 solution are added. Each flask is titrated to the end pointusing EDTA.

The explanation is given below-

Flask 1 2 3 Flask 1 2 3 initial burette reading 50 mL. 38 mL 28 mL volume EDTA required to chelate Ca²+ final burette reading 38 mL 28 mL 20 mL. total volume VEDTA Vuk ........ moles Ca* present in 25 mL water sample moles EDTA Average moles of Ca2+/L-water = Average grams of Ca2+/L-water = #7 Volume EDTA required to chelate all Ca moles Ca present in IL water sample ...moles ..grams

Flask 1 2 3 Flask 1 2 3 initial burette reading 50 mL. 38 mL 28 mL volume EDTA required to chelate Ca²+ final burette reading 38 mL 28 mL 20 mL. total volume VEDTA Vuk ........ moles Ca* present in 25 mL water sample moles EDTA Average moles of Ca2+/L-water = Average grams of Ca2+/L-water = #7 Volume EDTA required to chelate all Ca moles Ca present in IL water sample ...moles ..grams

Chemistry & Chemical Reactivity

10th Edition

ISBN:9781337399074

Author:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel

Publisher:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel

Chapter4: Stoichiometry: Quantitative Information About Chemical Reactions

Section4.9: Spectrophotometry

Problem 3.1ACP

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