Question

What is the ratio of uncomplexed to complexed to complexed `Zn^(2+)` ion in a solution that is `10 M "in" NH_(3) ` . If the stability constant of `[Zn(NH_(3))_(4)]^(2+)` is `3xx10^(9)`?
A. `3.3xx10^(-9)`
B. `3.3xx10^(-11)`
C. `3.3xx10^(-14)`
D. `3xx10^(-13)`

Answer 1

Correct Answer - C
`Zn^(2) +4NH_(3) hArr [Zn(NH_(3))_(4)]^(2+)`
`K_(f ) =([Zn(NH_(3))_(4)]^(2+))/([Zn^(2+)][NH_(3)]^(4)=3xx10^(9)`
`therefore ([Zn(NH_(3))_(4)]^(2+))/([Zn^(2+)]=[NH_(3)]^(4)xx3 xx10^(9)`
` = 10^(4) xx3xx10^(9) = 3xx10^(13)`
`therefore ([ Zn^(2+)])/([Zn(NH)_(3)_(4)]^(2+))=3.3xx10^(-14)`