Determine the [oh-] of a solution that is 0.125 m in co32-.

CO3^2 - + H2O H2CO3 + OH-

the equilibrium constant expression for this reaction

Kb = (HCO3-) (OH-) / CO3^-2

kb=2.0 x 10^-4

the concentration of both HCO3 - and OH - can be presented by X

therefore KB = (x) (x) / (CO3^-2)

2.0 x 10 ^-4 = (x) (x) / 0.125

multiply both side by 0.125

=2.5 x10^-5 = (x^2)

find square root

x=5 x 10^-3