Question

A solution of NaF is added dropwise to a solution that is 0.0532 M in Mg2+...

A solution of NaF is added dropwise to a solution that is 0.0532 M in Mg2+ and 1.43e-05 M in Y3+.

The Ksp of MgF2 is 5.16e-11.
The Ksp of YF3 is 8.62e-21.






(a) What concentration of F- is necessary to begin precipitation? (Neglect volume changes.)

[F-] =  M.



(b) Which cation precipitates first?

Mg2+Y3+     






(c) What is the concentration of F- when the second cation begins to precipitate?

[F-] =  M.

Homework Answers

Answer #1

a) Magnesium fluoride precipitate according to
Mg2+(aq) + 2 F⁻(aq) ←→ MgF2(s)

When MgF2 precipitates ion concentrations satisfy solubility product:
Ksp = [Mg2+] * [F-]2

Assuming NaF is concentrated enough, that only a small portion of solution is added till precipitation, the change of [Mg2+] due to dilution may be ignored. Hence:

b) Mg2+ will be precipitate first than Y3+

c) Yttrium fluoride precipitate according to
Y3+(aq) + 3 F⁻(aq) ←→ YF3(s)

When YF3 precipitates ion concentrations satisfy solubility product:
Ksp = [Y3+] * [F-]3

Assuming NaF is concentrated enough, that only a small portion of solution is added till precipitation, the change of [Y3+] due to dilution may be ignored. Hence:

Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
A solution of Na3PO4 is added dropwise to a solution that is 0.0219 M in Ca2+...
A solution of Na3PO4 is added dropwise to a solution that is 0.0219 M in Ca2+ and 7.03e-06 M in Al3+. The Ksp of Ca3(PO4)2 is 2.07e-33. The Ksp of AlPO4 is 9.84e-21. (a) What concentration of PO43- is necessary to begin precipitation? (Neglect volume changes.) [PO43-] = ___________ M. (b) Which cation precipitates first? Ca2+ Al3+     (c) What is the concentration of PO43- when the second cation begins to precipitate? [PO43-] = _____________ M.
A solution of NaSCN is added dropwise to a solution that is 0.0821 M in Hg22+...
A solution of NaSCN is added dropwise to a solution that is 0.0821 M in Hg22+ and 0.0142 M in Cu+. The Ksp of Hg2(SCN)2 is 3.2e-20. The Ksp of CuSCN is 1.77e-13. (a) What concentration of SCN- is necessary to begin precipitation? (Neglect volume changes.) (b) Which cation precipitates first? Hg2 2+ or Cu+ (c) What is the concentration of SCN- when the second cation begins to precipitate?
An aqueous solution of barium nitrate is added dropwise to a solution containing 0.10 M sulfate...
An aqueous solution of barium nitrate is added dropwise to a solution containing 0.10 M sulfate ions and 0.10 M fluoride ions. The Ksp value for barium sulfate = 1.1 x 10-10 and the Ksp value for barium fluoride = 1.7 x 10-6 a.) Which salt will precipitate from solution first? b.) What is the minimum [Ba2+] concentration necessary to precipitate the first salt? c.) What is the minimum [Ba2+] concentration necessary to precipitate the second salt? c.) What is...
Consider a solution that is 2.1×10−2 M in Fe2+ and 1.6×10−2 M in Mg2+. Part A...
Consider a solution that is 2.1×10−2 M in Fe2+ and 1.6×10−2 M in Mg2+. Part A If potassium carbonate is used to selectively precipitate one of the cations while leaving the other cation in solution, which cation will precipitate first? ANSWER: Fe 2+ Part B What minimum concentration of K2CO3 is required to cause the precipitation of the cation that precipitates first? ANSWER: [K2CO3] = 1.5×10−9 M Part C What is the remaining concentration of the cation that precipitates first,...
Consider a solution that is 2.5×10−2 M in Fe2+and 1.0×10−2 M in Mg2+. What is the...
Consider a solution that is 2.5×10−2 M in Fe2+and 1.0×10−2 M in Mg2+. What is the remaining concentration of the cation that precipitates first, when the other cation just begins to precipitate?
A solution contains Cr3+ ion and Mg2+ ion. The addition of 1.00 L of 1.55 M...
A solution contains Cr3+ ion and Mg2+ ion. The addition of 1.00 L of 1.55 M NaF solution is required to cause the complete precipitation of these ions as CrF3(s) and MgF2(s). The total mass of the precipitate is 49.8 g . Find the mass of Cr3+ in the original solution.
A solution contains Cr3+ ion and Mg2+ ion. The addition of 1.00 L of 1.54 M...
A solution contains Cr3+ ion and Mg2+ ion. The addition of 1.00 L of 1.54 M NaF solution is required to cause the complete precipitation of these ions as CrF3 (s) and MgF2 (s). The total mass of the precipitate is 49.6 g. Find the mass in grams of Cr3+ in the original solution.
2. A solution of K2SO4 is added to a solution that is 0.015 M in Ba^2+...
2. A solution of K2SO4 is added to a solution that is 0.015 M in Ba^2+ and 0.015 M in Sr^2+. a. What is the necessary concentration of sulfate ion to begin precipitation? b. Does Ba^+2 or Sr^+2 precipitate first? BaSO4: Ksp = 1.1 x 10^-10; SrSO4: Ksp = 3.2 x 10^-7
3. To a solution of 0.0100 M Al(NO3)3 and 0.0200 M CaCl2 , Na3PO4 is added....
3. To a solution of 0.0100 M Al(NO3)3 and 0.0200 M CaCl2 , Na3PO4 is added. The Ksp of AlPO4 is 9.8×10−22; The Ksp of Ca3(PO4)2 is 9.8×10−22. a) Determine which of these salts is more soluble in water. b) Calculate [PO43−] when the first cation begins to precipitate. c) Calculate the concentration of the first ion to precipitate, when the second ion begins to precipitate.
A solution is 0.085 M in Pb2+ and 0.025 M in Ag+. A. If selective precipitation...
A solution is 0.085 M in Pb2+ and 0.025 M in Ag+. A. If selective precipitation is to be achieved using NaCl, what minimum concentration of NaCl do you need to begin to precipitate the ion that precipitates first? B. What is the concentration of each ion left in solution at the point where the second ion begins to precipitate?