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)
