Question

Calculate the equilibrium constant, Ka, for the dissociation of a weak acid HA with an initial concentration of 0.10 M that ionizes to form H+ and A-. At equilibrium, the concentration of H+ is found to be 1.0 x 10^-5 M and the concentration of A- is 0.09 M.

Answer 1

To calculate the equilibrium constant, Ka, for the dissociation of a weak acid HA, we can use the following equation:Ka = [H+][A-] / [HA]At equilibrium, the concentration of H+ is 1.0 x 10^-5 M and the concentration of A- is 0.09 M. Since the initial concentration of HA is 0.10 M and it loses 1.0 x 10^-5 M to form H+ and A-, the equilibrium concentration of HA is:[HA] = 0.10 M - 1.0 x 10^-5 M = 0.09999 MNow we can plug these values into the Ka equation:Ka =  1.0 x 10^-5 M  0.09 M  /  0.09999 M Ka = 9.0 x 10^-7So, the equilibrium constant, Ka, for the dissociation of the weak acid HA is 9.0 x 10^-7.