[Firehchicken]

Hi, the answer to the question below is C. I do not understand why; isn't the concentration equal to the square root of the KsP???

[sjb]

What is the expression you have developed for Ksp?

[Firehchicken]

What is the expression you have developed for Ksp?

Ksp = [Zn2+][CN-]

is it not? Since it dissociated in a one to one ratio can we assume that their concentrations are equal.

[mjc123]

Is it dissociated in a 1:1 ratio?

[Firehchicken]

Is it dissociated in a 1:1 ratio?

Right, I understand it is dissociated in a 1:2 Zn:CN ratio, but i still can't figure out the answer.

By this logic it must follow that (assuming the concentrations of Zn and Cn are x) : x^3 = Ksp = 2.56 × 10^-13.

Taking the cube root does not give me an answer of 8.0 × 10^-5.

Back-tracking, cubing 8.0 × 10^-5 gives me a value of 5.12×10^-13, which is twice the Ksp value. There's something not quite right here

[Flatbutterfly]

Zn(CN)2(s) ⇋ Zn^2+ + 2CN^-
Ksp = [Zn^2+][CN^-]^2 = 2.56×10^-13
Let x mol of Zn(CN)2 dissolve then [Zn^2+] = x;  [CN^-] = 2x
Ksp = (x)(2x)^2 = 2.56×10^-13
4x^3 = 2.56×10^-13
x = 4×10^-5 M
The answer key is incorrect

[Borek]

x = 4×10^-5 M
The answer key is incorrect

What about

[CN^-] = 2x

[Flatbutterfly]

Yes - it occurred to me this morning that [CN^-] = 2x = 8x10^-5M but I could only see half the question posted.