(a) Anaerobic bacteria living at the bottom of a shallow inlet to a salt marsh are generating hydrogen sulfide as a by product of their metabolism. Although this compound is ordinarily found as a gas, it is reasonably soluble in water. What is the maximum concentration of dissolved hydrogen sulfide species (H2S, HS-, and S2-)that could theoretically accumulate in the waters of the inlet if the pH is 6.0?
(b) A small amount of dibromomethane has been spilled into the above inlet. Assume the partial pressure of the H2S is 0.1 atm. If the principal process that will affect the fate of this species is its reaction with HS-, for which the relevant rate constant is 5.25E-5 /M/sec, how many days will be required for the dibromomethane concentration to decrease to 10% of its initial value?