Consider the two dissociation reactions of aqueous hydrogen sulfide:
H2S(aq) + H2O(l) → HS–(aq) + H3O+(aq)(1)
HS–(aq) + H2O(l) → S2–(aq) + H3O+(aq)(2)
a) Write the expression for the Ka,2 and the pKa,2 of this weak acid.
Ka,2 =
pKa,2 =
b) Using the data in the thermodynamic tables, calculate ΔGo, Ka,2 , and pKa,2 at 298K. Note: You can treat the hydronium ion as H2O + H+(aq)
c) Assuming ΔHo to be independent of temperature, calculate Ka,2 at 80 oC.
H2S(aq) + H2O(l) → HS–(aq) + H3O+(aq)(1)
HS–(aq) + H2O(l) → S2–(aq) + H3O+(aq)(2)
a) Write the expression for the Ka,2 and the pKa,2 of this weak acid.
Ka,2 =
pKa,2 =
b) Using the data in the thermodynamic tables, calculate ΔGo, Ka,2 , and pKa,2 at 298K. Note: You can treat the hydronium ion as H2O + H+(aq)
c) Assuming ΔHo to be independent of temperature, calculate Ka,2 at 80 oC.