Question

An evil maniac has dumped one metric ton (1,000 kg) of lead nitrate into a Bayou feeding into the City of Houston water supply. Assume the bayou contains roughly 10⁶ L of water and it is naturally buffered to a pH of 7.000 (pH does not change).

a. What is the starting concentration of lead in this bayou in units ppb?

b. Will lead hydroxide precipitate under these conditions? Why or why not? [Note: Pb(OH)₂ has a K_sp of 1.4 * 10^-25]

c. How many grams of NaOH would you have to add to precipitate the maximum amount of lead hydroxide? (Hint: Remember you are in a buffer, so the hydroxide simply precipitates the lead).

d. Is the removal of lead by the precipitation of lead hydroxide a good strategy for protecting people? Why or why not?

Answer 1

. 1207. Molore Mass of PHNO.) = 3312 g.) mol Atomie Maus P6= 207.30. fol. 33112 g. Pb (No. contains 207-2g. of Pb ...1000 kg Polac), contains (207:20) 2,106 L of water contains 16.256+ 10 alph - n. 12 of Water contains 590210 g- of Pb .Concentration of head = 15-902*** ppb b. M B (P5*] 5690221002-848-10" [04-3= 10mbele since, Vpitz melen/L. :: [Pb*)[0H- )= 2.858 210-75 rolos/. Kot .: Pb(OH), will precipitate under there conditions 20702

even sin C) Simca, Polov)_will provifitale even in heti 7 no Addition of NaOH is needed d) Precipitation of Pb (olt), is not a Good Strategy, since lit involves excesh Water and thus becomes an Inefficient technique Technique, tone better!! Technique is rather Exchange