(3)0.1 mol/L NaC2O [H]+[HC2O,]+20]=[OH] 20K,=20×104=2×103<e 舍弃[H] HCO1=[OH] 400K=400X10-0<c 10 1×109=32×106 [H]=3.1×109 看作NaOH滴定HCO至第二计量点 [T']=[OH] [D']=[H]+2HC2O]+[HC,O]=[HCO] [HC201g=[OH]g=32×109（3）0.1 mol/L Na2C2O4 [H+] + [HC2O4-] + 2[H2C2O4] = [OH-] Ka = × = × < c − 4 −3 20 20 10 2 10 2 舍弃[H+] [HC2O4-] = [OH-] Kb = < c × −10 400 400 10 1 9 6 4 14 [ ] 3.1 10 3.2 10 1 10 10 [ ] 0.1 1 + − − − − − = × = × × = = × H OH cKb 看作 NaOH 滴定 H2C2O4至第二计量点 6 2 4 2 2 4 2 4 2 4 [ ] [ ] 3.2 10 [ '] [ ] 2[ ] [ ] [ ] [ '] [ ] − − − + − − − = = × = + + = = HC O eq OH eq D H H C O HC O HC O T OH