Ka(HCOOH) = 1.77x10-4-------------------HCOOH = H+ + HCOO-初（mol/L) 0.1 0 0平（mol/L) 0.1-x x x[HCOO-] [ H+] / [HCOOH] = Kax^2 / (0.1 - x) = Ka根据判断：c(HCOOH) / Ka > 500 时,可以简化：0.1 - x ≈ 0....