Na2HPO4电荷守恒,[Na+]+[H+]=[OH-]+[H2PO4-]+2[(HPO4)2-]+3[(PO4)3-]物料守恒,[Na+]=2[(PO4)3-]+2[(HPO4)2-]+2[H2PO4-]+2[H3PO4]质子守恒,[OH-]+[(PO4)3-]=[H2PO4-]+2[H3PO4]+[H+]
