Foe Fe(OH)2, Ksp=8 x 10^-16. What is the molar concentration of OH- in a saturated Fe(OH)2 solution?
let x be the conc of the Fe ions
Ksp= x*(2x)^2
solve for x.
then the OH is 2x
To find the molar concentration of OH- in a saturated Fe(OH)2 solution, we need to determine the value of [OH-] by using the solubility product constant (Ksp) and the molar concentration of Fe(OH)2.
The equation for the solubility product constant is:
Ksp = [Fe2+][OH-]^2
Since the stoichiometric coefficient for OH- in Fe(OH)2 is 2, we need to find the value of [OH-] raised to the power of 2.
Let's assume the molar concentration of Fe(OH)2 is x. Therefore, the molar concentration of [Fe2+] is also x.
Ksp = (x)([OH-])^2
Given that Ksp for Fe(OH)2 is 8 x 10^-16, we can substitute this value into the equation:
8 x 10^-16 = (x)([OH-])^2
To solve for [OH-], we can rearrange the equation:
[OH-]^2 = (8 x 10^-16) / x
Taking the square root of both sides gives us:
[OH-] = √((8 x 10^-16) / x)
Note that this equation provides the molar concentration of OH- in terms of x, which represents the molar concentration of Fe(OH)2.
So, we need more information to determine the molar concentration of OH- in a saturated Fe(OH)2 solution.
To find the molar concentration of OH- in a saturated Fe(OH)2 solution, we can use the solubility product constant (Ksp) expression for Fe(OH)2.
The balanced equation for the dissociation of Fe(OH)2 is:
Fe(OH)2(s) ⇌ Fe2+(aq) + 2OH-(aq)
The Ksp expression is then:
Ksp = [Fe2+][OH-]^2
Since Fe(OH)2 is a strong base, it will fully dissociate in water, resulting in a 1:2 molar ratio between Fe2+ and OH-. Therefore, the molar concentration of OH- is twice the molar concentration of Fe(OH)2.
Let's assume the molar concentration of Fe(OH)2 is x M. Thus, the molar concentration of OH- is 2x M.
Now, we can substitute these values into the Ksp expression:
Ksp = [Fe2+][OH-]^2
8 x 10^-16 = x * (2x)^2
8 x 10^-16 = 4x^3
Rearranging the equation:
x^3 = (8 x 10^-16) / 4 = 2 x 10^-16
Taking the cube root of both sides to solve for x:
x = (2 x 10^-16)^(1/3)
Using a calculator, we find:
x ≈ 1.26 x 10^-6 M
So, the molar concentration of OH- in a saturated Fe(OH)2 solution is approximately 1.26 x 10^-6 M.