Assignment:
Early groups used Pb plumbing in their homes more than 2000 years ago. This Pb pipe has since corroded in the soil to form cerrusite (PbCO3) and hydrocerrusite ( Pb3(CO3)2(OH)2 ).
Essington et al., 2004. The soil mineralogy of lead at Horace's
Villa. Soil Sci. Soc. Am. J., 68, 979)
https://soil.scijournals.org/cgi/content/full/68/3/979
(a) Assuming a CO2 partial pressure in the soil of about 0.02 atm , calculate the free lead ion solubility, (Pb2+), in soil solution at pH 5, 6, 7 and 8.
(b) Plot the calculated log (Pb2+) versus pH for these minerals on the same graph, with pH on the x-axis.
Reaction Equilibrium Constants :
PbCO3(s) + 2H+ = Pb2+ + CO2(g) + H2O log Ko = 4.89
Pb3(CO3)2(OH)2(s) + 6H+ = 3 Pb2+ + 2 CO2(g) + 4 H2O log Ko = 18.49
Provide complete and step by step solution for the question and show calculations and use formulas.