Respuesta :

Products over reactants: 

HS- + H2O ----> H2S + OH- 

The expression represents Kb for HS–
Since OH- is in the expression we're looking for Kb (which is for finding the pOH out).

And since K's are in relation to the reactant (which is in the denominator below [tex] \frac{x}{y} [/tex] ), the solution is Kb for HS-