(2)计量点前vc> NAo 溶液pH值取决于剩余HC浓度[H+]=CHCl ·当V(NaOH)=1998m(误差-0.1%) hcI NaOH儿HCl HCl NaoH [ HI (20.00-19.98)×0.1000 =500×103mol/l 20.00+1998 pH=430 22 (2) 计量点前VHCl>VNaOH • 溶液pH值取决于剩余HCl浓度 [H+]=CHCl • 当V(NaOH)=19.98ml(误差-0.1%)   HCl NaOH HCl NaOH HCl V V V V C H + − = + ( ) H  5.0 0 1 0 mol /l 2 0.0 0 1 9.9 8 + (2 0.0 0 1 9.9 8) 0.1000 −5 =  + −  = pH=4.30