若在pH10的氨性缓冲液中用EDTA标准溶液滴定Ni2+,已知lgKNiY=18.67,lgαY(H)=0.45,lgαNi(NH3)=4.17,此时.AlgKNiY=18.22,不能准确滴定Ni2+BlgKNiY=14.05,能准确滴定Ni2+ClgKNiY=14.50,能准确滴定Ni2+DlgKNiY=14.50,不能

Question

若在pH10的氨性缓冲液中用EDTA标准溶液滴定Ni2+,已知lgKNiY=18.67,lgαY(H)=0.45,lgαNi(NH3)=4.17,
此时____.
A lgKNiY=18.22,不能准确滴定Ni2+
B lgKNiY=14.05,能准确滴定Ni2+
C lgKNiY=14.50,能准确滴定Ni2+
D lgKNiY=14.50,不能准确滴定Ni2+

Answer 1

应选B,lgKNiY=18.67-0.45-4.17=14.05,此式子中的K为条件形成常数,一般说当条件形成常数大于8时金属离子可被准确滴定（终点误差小于0.1%）