Chemistry solubility and precipitate

AI Thread Summary
The discussion revolves around calculating the mass of KF needed to produce a specific amount of BaF2 precipitate in a solution containing Ba(NO3)2 and NaF. The Ksp of BaF2 is given as 1.84 x 10^-7, and the calculations involve determining the concentration of fluoride ions required for saturation. The solution indicates that an added concentration of KF of 0.00833 mol/L is necessary, which translates to a mass of approximately 0.484 g of KF. The approach taken in the calculations appears to be correct, though the final answer has not been verified. Overall, the discussion emphasizes the relationship between solubility product constants and precipitate formation in chemical solutions.
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Homework Statement



A solution contains 1.73 x 10^-3 mol/L of Ba(NO3)2(aq) and 1.2 x 10^-3 moles of NaF. What mass of KF added to this solution would produce 2.7 x 10^-3g of precipitate from this solution if the Ksp of BaF2 is
1.84 x 10-7 and you have 1.0L of solution?

Homework Equations


The Attempt at a Solution


Mass of BaF2 = 2.7*10^-3g/ 175.3 (molar mass)
= 1.5*10^-5 moles/L

Ksp = (ba) (F)^2
1.84*10^-7 = (1.73 x 10^-3 - 1.5*10^-5) (Concentration of F)^2
(1.84*10^-7 /.001715)^.5 = (Concentration of F)
.0103 = (Concentration of F at Saturation Point)

2 x 10^-3 moles of NaF + (Added Concentration of KF) - 2(1.5*10^-5 moles/L) = .0103

(Added Concentration of KF) = .00833 mol/L
.00833 mol/L * (Molar Mass of KF 58.1) = .484 g of KF

Did I answer this Question Correctly
 
Last edited:
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I have not checked the answer, but the approach looks OK.
 
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