A common method for preparing a precipitate is to mix solutions containing the component ions of the compound you want to be a precipitate. Consider the mixture of 0.1 Liters of 0.3 M calcium fluoride is mixed with 0.2 Liters of 0.06 sodium nitrate. Does a precipitate form and what is it?
I know that the CaF2 precipitates because its ion product is greater than the solubility product constant. I'm not sure about the sodium nitrate.
These are the answers I have to choose from.
a. Nothing will precipitate out
b. Yes, CaF2 will precipitate out
c. Yes, NaNO3 will precipitate out
d. At first both NaNO3 and CaF2 will precipitate out but due to the common ion effect, both will dissolve back into solution.
e. At first both NaNO3 and CaF2 will precipitate out.
2007-03-11 11:36:38 · 2 answers · asked by Ulna G 1 in Science & Mathematics ➔ Chemistry
The molar solubility of CaF2 is approximately 2 *10^-4 M
You can't have a 0.3 M solution of calcium fluoride. I think you mistyped the question: you should have calcium nitrate and sodium fluoride mixing.
Sodium nitrate is very soluble so only CaF2 precipitates (once you mix you'll have [Ca+2]o=0.3*0.1/0.3 =0.1 and [F-]o= 0.06*0.2/0.3 = 0.04, so [Ca+2]o (F-]o^2= 0.1*0.04^2= 16*10^-5>Ksp) . Thus the correct answer is b
2007-03-12 02:03:09 · answer #1 · answered by bellerophon 6 · 0⤊ 0⤋
i am a smart teacher and (B) is correct
2007-03-11 18:50:49 · answer #2 · answered by pcmpq386 1 · 0⤊ 0⤋