ksp to concentration discrepancy

[wall1two]

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BaF2--> Ba + 2F the Ksp is 1 * 10^-6

what is the concentration of F- ions in the solution

i thought ksp= x*4x^2= 4x^3 for this salt

i did this 2*(3rd root ((1*10^-6)/4)) = 2x = [F-]

the princeton review sets it up like this ksp= [Ba][F-]^2 = (x/2)(x)^2

my method works in destroyer, so why doesn't it work here?

 

[wizi]

BaF2--> Ba + 2F the Ksp is 1 * 10^-6

what is the concentration of F- ions in the solution

i thought ksp= x*4x^2= 4x^3 for this salt

i did this 2*(3rd root ((1*10^-6)/4)) = 2x = [F-]

the princeton review sets it up like this ksp= [Ba][F-]^2 = (x/2)(x)^2

my method works in destroyer, so why doesn't it work here?

Your method: 2x = [F-]

Princeton: x = [F-] because they assign x = 2F --> Ba = x/2 --> Ksp = x/2 * x^2. If your method works for you, stick with it. Princeton is doing the same thing but they assign different value. Stick with what works for you.