Answer Happy

Part B-Flint Water Case Study 1) Untreated lead pipes can react with oxygen dissolved in water to produce PbO. The molar mass of Pbo is 223.2 g/mole, and its solubility in water is 1.7x10g/100 ml. Calculate the Ksp for Pbo. [5] 2) Calculate the Ksp for each of these compounds. [4] Ksp Compound Pbco Pb3(PO4)2 Molar Mass (g/mole) 267.2 811.5 Solubility (g/100 mL) 1.1x104 1.4x105 3) Write the Ksp expressions (NOT the value, just the equation) for each of the lead- containing compounds. Remember to include superscripts when appropriate. [6] Compound Ksp expression Ksp = 4) Use the Ksp values to calculate how much lead is solubilized in 1.0 L water run through untreated (PbO) and treated (PbCO3 or Pb3(PO4)2) pipes. Report the concentration for each condition in the table below [12] Compound Soluble (Pb2+] (M) O PbO (untreated) PbCO3 Pb3(PO4)2
5) The drinking water in Flint, Michigan was provided by the City of Detroit prior to April of 2013. The City of Detroit also had many lead pipes, but it controlled leeching of lead into the drinking water by adding Na3PO4 at a concentration of 1.2x10%M a. Write out the dissociation equation for Na3PO4. Include states for each chemical species. [4] b. Calculate the molarity of the phosphate ion after dissolving Na3PO4 in 1.0 L of water. Assume this is a strong electrolyte and completely dissociates [4] c. Use the Ksp of Pb3(PO4)2 and the molarity of the phosphate ion in treated water to determine the molar concentration of dissolved lead in treated water. [4] d. Compare the molar concentration of dissolved lead in the treated water (part c) to the concentration of dissolved lead from the lead phosphate passivation layer you determined for untreated water (Question 4). Which is higher? Hint: This is an example of the common ion effect. [4]