分析化学武汉大学第五版答案

8.解：PH=5.0时，lgKlg?Y(H)?6.45lg?Y(Cd)?lgspKCdYCCdZnY'?4.8?pZnep?4.8

lgK'ZnY?lglgKZnY?lg(?Y(H)??Y(Cd))?Cd(I)sp KCdY?1016.46 CCd?0.005mol?L?1?Cd(I)?1?102.10?102.43?104.49?105.41?lg?Cd(I)?5.46?lg?Y(Cd)?8.70lgK'ZnY?16.50?lg(106.45?108.70)?7.80sppZnsp?0.5(lgK'ZnY?pCZn)?5.05?VpZn??0.25K'C 10.解：设Al3+浓度为0.010mol/L，则由Al(OH)3的Ksp

ZnYEt?10VpZn?10?VpZnspZn??0.22%计算可得Al发生水解时pH=3.7。要想在加入EDTA时，Al不发生水解，pH应小于3.7。

[HAc][H?]10?5?Ac(H?)??1?1??1??4.74?1.55[Ac?]Ka10C0.31[Ac?]?HAc?mol?L?1?0.2mol?L?1?Ac(H?)1.55Pb2?3+

3+

12.解：?a. ?1??[Ac(Ac?)1?]??2[Ac?]2?1?101.9?0.2?103.8?0.04?102.43lg? ? 6.45

Y(H?)

lgK'PbY?lgKPbY?lg?Pb2?(Ac?)?lg?Y(H?)?18.04?2.43?6.45?9.16pPb'sp?6.08 pPbep?7.0 pPb'ep?7.0?2.43?4.57?pPb'??pPb??1.51 Et?10VpPb?10?VpPbK'PbYCspPb??2.7%

b.

15. 解: 由Ksp ，测Th时pH<3.2,测La时pH<8.4，查酸效应曲线（数据）可知，测Th时 pH?2较好，为消除La的干扰，宜选pH<2.5,因此侧Th可在稀酸中进行；侧La在pH5-6较合适，可选在六亚甲基四胺缓冲溶液中进行。

18. 解: 由题意可知

?Pb??Sn?0.03?35?118.69?100%?62.31%0.2?1000lgK'PbY?lgKPbY?lg?Y(H)?18.04?6.45?11.5911.59?3?7.30 pPbep?7.0 ?pPb??0.30210VpPb?10?VpPbEt???0.007%spK'PbYCPbpPbsp?

21. 解: 据题中计量关系得：

0.2014(0.03?50?0.03?3.0?0.03?35)?207.2?100%?37.29%0.2000?1000

0.025?0.03?0.0036?0.001?10??254.2?2????100%?98.45$. 解: 据题中计量关系得：

?Ni?0.05831?0.02614?58.693?100%?63.33%0.7176

?Fe?(0.03544?0.05831?0.02614?0.05831)?5?55.845?100%0.7176

=21.10%

?Cr?(0.05?0.05831?0.00621?0.06316?0.03544?0.05831)?5?51.9960.7176

?100%=16.55%）