What is the equilibrium constant for the following reaction that occurs when disodium citrate (Na2HC6H5O7) dissolves in water at 25ºC? The acid dissociation constants for citric acid, H3C6H5O7, are: Ka1 = 7.4 × 10–4, Ka2 =1.7 × 10–5, and Ka3 = 4.0 × 10–7. HC6H5O72–(aq) H2O(l) ⇌ H2C6H5O7–(aq) OH–(aq