用K2Cr2O7滴定Fe2+,在化學(xué)計(jì)量點(diǎn)時(shí),有關(guān)離子濃度的關(guān)系是()
A.A B.B C.C D.D
A.0.2g左右 B.0.2g~0.4g C.0.4g~0.8g D.0.8g~1.6g
A.[NH3]=0.20mol/L B.[NH3]+[Ag(NH3)+]+[Ag(NH3)2+]=0.20mol/L C.[NH3]+[Ag(NH3)+]+2[Ag(NH3)2+]=0.20mol/L D.[NH3]+[Ag(NH3)+]+2[Ag(NH3)2+]+[NH4+]=0.20mol/L