Problem 2 EDTA Titration Lab Data (80 Points) The following data was used in a s

Question

Problem 2 EDTA Titration Lab Data (80 Points) The following data was used in a series for quantifying several common contaminants in drinking water: Pb2+, Hg2+, Cu and SO In order to analyze all of these, multiple EDTA titrations were performed. Each will be described individually below. Assume any of this data could be outliers (it is raw, laboratory data), and ALL relevant statistics should be performed! Your task will be to determine if these values (statistically) exceed the levels set by the EPA as safe for a natural body of water. Safe levels are given below (taken from: www.epa.gov): Safe Levels Cu 1.3 ppm Pb 0.015 ppm Hg 0.002 ppm SO4 250 ppm "Ppm" is parts per million and is defined as ug/mL. EDTA Standardization (10 Points; 5 Points Standardization, 5 Points Error) The EDTA solution was initially standardized against Mg identical to the work we did in the laboratory this semester using Eriochrome Black T as the indicator at a pH of 10.00. 25.00 mL aliquots of Migz solution were used. A stock Mg solution was created by dissolving 0.4673 g of magnesium nitrate hexahydrate in 250.00 mL of distilled water. This solution was diluted by taking 2.5 mL and diluting to 250 mL to create the stock solution used in the titrations given. EDTA Standardization Trial VEDTA (mL) 33.07 31.89 36.51 32.18 33.21 6 32.26

Explanation / Answer

molar concentration of Mg stock solution = 0.4673 g/256.41 g/mol x 0.250 L

                                                                  = 0.0073 M

molar concentration of Mg stock (diluted) = 0.0073 M x 2.5 ml/250 ml

                                                                  = 7.3 x 10^-5 M

Standardization of EDTA

moles of Mg used = 7.3 x 10^-5 M x 25 ml

                              = 1.825 mmol

moles of EDTA = moles of Mg

molar concentration of EDTA solution = moles of EDTA/volume of EDTA solution

So,

Trial 1 : molarity of EDTA solution = 1.825/33.07 = 0.0552 M

Trial 2 : molarity of EDTA solution = 1.825/31.89 = 0.0572 M

Trial 3 : molarity of EDTA solution = 1.825/36.51 = 0.0500 M

Trial 4 : molarity of EDTA solution = 1.825/32.18 = 0.0567 M

Trial 5 : molarity of EDTA solution = 1.825/33.21 = 0.0550 M

Trial 6 : molarity of EDTA solution = 1.825/32.26 = 0.0565 M

average molarity of EDTA solution = 0.0551 M

Related Questions

Navigate

• Browse (All)
• Browse P
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.