only need 2b and 2C

please explain

An enclosed reactor contains a solution of iron sulfide (FeS(s)). The air above the solution in this reactor contains hydrogen sulfide (H2S) gas. You know H2S(aq) (which forms from hydrogen sulfide gas dissolution) is a weak acid and dissociates according to the following equations: a. Write the charge balance expression for this chemical equilibrium reaction system. b. Solve for the concentrations of: [H2S(aq)], [HS ] [S2], and [Fe2+], and [OH] in terms of PH2S,,K 's and [H+]. c. You measure the pH of the water in this enclosed reactor to be 8.5. Calculate the partial pressure of H2S gas (in atm) in the air above the liquid inside this enclosed reactor. Start by re-writing your charge balance expression in terms of the species concentrations you solved for in (b)