What is the equilibrium [OH–] in 0.1413 M H₂CO₃ ? H CO H O H O HCO (Ka = 4.30 ×10–7)

Let us consider the given buffer reaction as follows: - 2 3 2 3 3 - 7 a 3 3 2 3 a H CO + H O HCO H O initial        0.1413                       0         0 at eqm.   0.1413 x                  x         x K [HCO ][H O ]/[H CO ] 4.30 10 Now,K (x)(x) / 0.1413 x 4.30 x 7 2 7 a 3 14 w 14 3 11 10 x 4.30 10 0.1413 x x is very small as compared to K . Therefore, it is neglected in higher terms. x [H ] 2.4 10 K [H ][OH ] 10 [OH ] 10 / 2.4 10 4.06 10 M x >> x x x x