A solution is prepared in which a trace or small amount of Fe+2 is added to a much larger amount of solution in which the [OH]- is 1.0M*10^-2. some Fe(OH)2 precipitates. the value of Ksp for the salt is 8.0*10^-10. assuming that the hydroxide ion concentration is 1.0M*10^-2 calculate the Fe+2 concentration.
it's 8*10^-6 because the hydroxide concentration is squared. trust me, we went over this in my ap chem class (I got that originally wrong too)
Ksp = (Fe^+2)(OH^-)^2 = 8.0E-10
Plug in 1.0E-2 for (OH)2 and solve for Fe^+2.
Why did the iron go to school?
Because it wanted to get smarter and become an Fe-nomenal student!
To calculate the Fe+2 concentration, we need to use the solubility product constant (Ksp) equation for Fe(OH)2. The equation is as follows:
Ksp = [Fe+2][OH-]^2
We are given that the [OH-] concentration is 1.0M*10^-2 and the Ksp value is 8.0*10^-10. Let's plug in the values:
8.0*10^-10 = [Fe+2](1.0M*10^-2)^2
Simplifying the equation, we have:
8.0*10^-10 = [Fe+2](1.0M*10^-4)
To isolate [Fe+2], we divide both sides of the equation by 1.0M*10^-4:
[Fe+2] = (8.0*10^-10) / (1.0M*10^-4)
Calculating this, we find that the Fe+2 concentration is approximately 8.0*10^-6 M.
So, the Fe+2 concentration in the solution is approximately 8.0*10^-6 M.
To calculate the concentration of Fe+2 in the solution, we can use the solubility product constant (Ksp) for Fe(OH)2, as well as the hydroxide ion concentration.
The balanced chemical equation for the precipitation reaction is:
Fe+2 + 2OH- → Fe(OH)2
The Ksp expression for this reaction is:
Ksp = [Fe+2][OH-]^2
Given values:
[OH-] = 1.0M * 10^-2
Ksp = 8.0 * 10^-10
Since the concentration of OH- is much larger than that of Fe+2, we can assume that the concentration of OH- remains essentially constant after precipitation occurs. Therefore, we can consider the concentration of OH- to be the same as its initial value.
Let's assume the concentration of Fe+2 is 'x'. Since 2 moles of OH- react with 1 mole of Fe+2, the concentration of OH- remaining after precipitation is 1.0M * 10^-2 - 2x.
Substituting these values into the Ksp expression, we get:
Ksp = x * (1.0M * 10^-2 - 2x)^2
Now we can solve for x. Rearrange the equation and take the square root of both sides to get:
√Ksp = x * (1.0M * 10^-2 - 2x)
Simplify the equation:
x = √Ksp / (1.0M * 10^-2 - 2x)
Now we substitute the value of Ksp into the equation:
x = √(8.0 * 10^-10) / (1.0M * 10^-2 - 2x)
Solve the equation for x using numerical methods or approximation techniques, such as iteration.
By solving the equation, you will find the concentration of Fe+2 in the solution.
I got 8*10^-8
Is this correct?