In a saturated solution of Zn(OH)2 at 25 degrees Celsius the value of [OH-] is 2.0x10^-6M. What is the value of the solubility-product constant, Ksp, for Zn(OH)2 at 25 degrees Celsius?
A. 4x10^-18
B. 8x10^-18
C. 1.6x10^-17
D. 4x10^-12
E. 2x10^-6
Help?
Thank you!
Ksp = (1x10^-6)(2x10^-6)^2
Ksp = 4.0 x 10^-18
Well, it seems like Zn(OH)2 is feeling quite a bit shy at 25 degrees Celsius with such a low [OH-] value of 2.0x10^-6M. It just wants to hide away in the corners of the solution!
To find the solubility-product constant, Ksp, we need to look at the balanced equation for the dissolution of Zn(OH)2:
Zn(OH)2 ⇌ Zn2+ + 2OH-
Ksp is the product of the concentrations of the dissociated ions raised to the power of their respective stoichiometric coefficients. In this case, it's the concentration of [Zn2+] multiplied by the concentration of [OH-] squared.
Now, based on the given information, we have [OH-] = 2.0x10^-6M. But we don't have the concentration of [Zn2+] yet.
Hmm, it seems like Zn2+ is leaving us hanging and wants us to figure it out ourselves. Well, we can use the fact that the dissociation equation shows a 1:1 ratio between Zn2+ and OH-, meaning the concentration of [Zn2+] will also be 2.0x10^-6M.
Finally, we can calculate Ksp by plugging in the values we know into the equation:
Ksp = [Zn2+][OH-]^2
= (2.0x10^-6M)(2.0x10^-6M)^2
= (2.0x10^-6M)(4.0x10^-12M^2)
If you crunch the numbers, you'll find that the value of Ksp is 8x10^-18. So the answer is B!
Hope that brings a smile to your face!
To find the value of the solubility-product constant, Ksp, for Zn(OH)2 at 25 degrees Celsius, you first need to understand the equation and concepts related to the solubility product.
The general solubility-product expression for any compound is given by multiplying the concentrations of the dissolved ions raised to the power of their stoichiometric coefficients from the balanced chemical equation.
For Zn(OH)2, the balanced chemical equation is:
Zn(OH)2 ⇌ Zn2+ + 2OH-
The concentration of Zn2+ ions in the solution is zero because Zn(OH)2 is a sparingly soluble compound. Hence, the equilibrium expression for the solubility product becomes:
Ksp = [Zn2+][OH-]²
Given that the concentration of [OH-] in the saturated solution of Zn(OH)2 at 25 degrees Celsius is 2.0x10^-6 M, we can substitute this value into the equilibrium expression:
Ksp = [Zn2+][(2.0x10^-6 M)²]
Now, since [Zn2+] is zero in the saturated solution (as it is not mentioned), we can simplify the equation further:
Ksp = 0 x (2.0x10^-6 M)²
Ksp = 0
Therefore, the value of the solubility-product constant, Ksp, for Zn(OH)2 at 25 degrees Celsius is 0.
None of the answer choices (A, B, C, D, E) match this result.
I hope this clarifies the concept for you!
tyrtyy
npnppnl
Zn(OH)2 ==> Zn^+2 + 2OH^-
Ksp = (Zn^+2)(OH^-)^2
(OH^-) = 2 x 10^-6 M.
(Zn^+2) must be 1 x 10^-6 M
Substitute into Ksp and solve.