CO32- + H2O ←→ HCO3- + OH-
HCO3- + H2O ←→ H2CO3 + OH-
Ka1 = c(HCO32-) * c(OH-) / c(CO32-) = 4.2×10^-7
设有x mol/L CO32- 参与第一层水解
x^2 / (0.1 - x) = 4.2×10^-7
解出x = 2.05 * 10^-4
Ka2 = c(H2CO3) * c(OH-) / c(HCO3-) = 5.6×10^-11
设有x mol/L HCO3- 参与第二层水解
x^2 / (2.05 * 10^4 - x) = 5.6×10^-11
解出x = 1.07 * 10^-7
c(OH) = 2.05 * 10^-4 + 1.07 * 10^-7 = 2.05 * 10^-4
pOH = -lgc(OH) = 3.7
pH = 14 - 3.7 = 10.3
c(H2CO3) = 1.07 * 10^-7mol/L
c((CO3)^2-) = 0.1 - 2.05 * 10^-4 = 0.1mol/L