18
已知: H3PO4的pKa1 = 2.12, pKa2 = 7.20, pKa3 = 12.36, 调节磷酸盐溶液的pH至6.0时,其各有关存在形式浓度间的关系是---------------------------( C )
(A) [HPO42-] > [H2PO4-] > [PO43-] (B) [HPO42-] > [PO43-] > [H2PO4-] (C) [H2PO4-] > [HPO42-] > [H3PO4] (D) [H3PO4] > [H2PO4-] > [HPO42-] 19
今有(a)NaH2PO4,(b)KH2PO4和(c)NH4H2PO4三种溶液,其浓度c(NaH2PO4) = c(KH2PO4) = c(NH4H2PO4) = 0.10mol/L, 则三种溶液的pH的关系是----( A )
[已知 H3PO4的pKa1~pKa3分别是2.12、7.20、12.36; pKa(NH4+) = 9.26] (A) a = b = c (B) a c (D) a = b
用NaOH溶液滴定H3PO4溶液至pH = 4.7时,溶液的简化质子条件为-( C ) (H3PO4的pKa1~pKa3分别是2.12、7.20、12.36)
(A) [H3PO4] = [H2PO4-] (B) [H2PO4-] = [HPO42-] (C) [H3PO4] = [HPO42-] (D) [H3PO4] = 2[PO43-]
主要成分：H2PO4-，[H+]=[H3PO4]－[HPO42-]－2[PO43-]，由于[H+]和[PO43-]很小，可忽略 21
于60 mL 0.10mol/L Na2CO3溶液中加入40 mL 0.15mol/L HCl溶液,所得溶液的简化质子条件是------------------------------------------( C )
(A) [H2CO3] = [HCO3-] (B) [HCO3-] = [CO32-] (C) [H2CO3] = [CO32-] (D) [H2CO3] = [H+] 主要成分：HCO3-，[H+]=[CO32-]－[H2CO3] 可忽略[H+] 22
0.1 mol/L Ag(NH3)2+溶液的物料平衡式是--------------------( D ) (A) [Ag+] = [NH3] = 0.1 mol/L (B) 2[Ag+] = [NH3] = 0.2 mol/L
(C) [Ag+]+[Ag(NH3)+]+2[Ag(NH3)2+] = 0.1 mol/L (D) [NH3]+[Ag(NH3)+]+2[Ag(NH3)2+] = 0.2 mol/L 23
含0.10mol/L HCl和0.20mol/L H2SO4的混合溶液的质子条件式是---( C ) (A) [H+] = [OH-]+[Cl-]+[SO4