HCOOH (aq) + H2O (l) ⇄ H3O+ (aq) + HCOO- (aq)


Ka = 1.8 × 10-4 at 25°C

I [HCOOH] Percent Ion E [H3O+]

0.150 3.4% 5.1 × 10^-3

0.100 4.2% 4.2 × 10^-3

0.0500 5.8% 2.9 × 10^-3


The equilibrium for the acid ionization of HCOOH is represented by the equation above and the table gives the percent ionization for HCOOH at different initial concentrations of the weak acid at 25°C. Based on the information, what is true for a 0.125M aqueous solution of HCOOH?