Question

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.

Homework Answers

Answer #1

a)

the salt which is most soluble (ignoring Al(NO3)3 CaCl2 and Na3PO4)

For solubility comparisson:

AlPO4:

AB <-> A+ + B-; Ksp = [A+][B-] = S*S = S^2 --> S = sqrt(Ksp)

S = sqrt(9.8*10^-22) = 3.13049*10^-11 M

Ca3(PO4)2

A3B2 <-->3A+2 + 2B-3; Ksp = [A+2]^3[B-3]^2 = (3S)^3 * (2S)^2 = 108*S^5 --> S = (Ksp/108)^(1/5)

S = ((9.8*10^-22)/(108))^(1/5)

S = 2.4635*10^-5

clearly,

Ca3(PO4)2 is much more soluble

b)

when AlPO4 starts to precipitate

Ksp = [Al+3][PO4-3]

9.8*10^-22 = (0.01)*[PO4-3]

[PO4-3] = 9.8*10^-20 M

c)

find [PO4-3] left when Ca3(PO4)2 precipitates

Ksp = [Ca+2]^3[PO4-3]^2

9.8*10^-22 = (0.02)^3 * [PO4-3]^2

sqrt((9.8*10^-22) / ((0.02)^3)) =  [PO4-3]

1.1067*10^-8 =  [PO4-3]

get [Al+3]

Ksp = [Al+3][PO4-3]

9.8*10^-22 = ([Al+3])*(1.1067*10^-8)

[Al+3] = (9.8*10^-22 ) / ((1.1067*10^-8)) = 8.855*10^-14 M

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 contains 0.0350 M Ca2 and 0.0100 M Sr2 .What is the concentration of the...
A solution contains 0.0350 M Ca2 and 0.0100 M Sr2 .What is the concentration of the first cation when the second starts to precipitate?
A 1.0L aqueous solution contains 0.25M PO43-. Solid indium nitrate In(NO3)3, is slowly added to the...
A 1.0L aqueous solution contains 0.25M PO43-. Solid indium nitrate In(NO3)3, is slowly added to the solution. The Ksp for InPO4=2.3x10-22 and Ksp for In(OH)3=1.3x10-37. Assuming that the volume remains constant, calculate the following: The [In3+] when InPO4 first starts to precipitate. The [In3+] when In(OH)3 first starts to precipitate. The [PO43-] when In(OH)3 first starts to precipitate. I understand the neccessity to make ICE tables and calculate the concentrations, however my study group cant seem to figure out why...
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.
A solution is 0.10 M Pb(NO3)2 and 0.10 M AgNO3. If solid NaCl is added to...
A solution is 0.10 M Pb(NO3)2 and 0.10 M AgNO3. If solid NaCl is added to the solution, what is [Ag+] when PbCl2 begins to precipitate? (Ksp PbCl2 = 1.7 x 10-5; AgCl = 1.8 x 10-10) A solution is 0.10 M Pb(NO3)2 and 0.10 M AgNO3. If solid NaCl is added to the solution, what is [Ag+] when PbCl2 begins to precipitate? (Ksp PbCl2 = 1.7 x 10-5; AgCl = 1.8 x 10-10)
An aqueous solution of sodium fluoride is slowly added to a water sample that contains barium...
An aqueous solution of sodium fluoride is slowly added to a water sample that contains barium ion (4.15×10-2 M ) and calcium ion (3.55×10-2 M ). The Ksp of barium fluoride is 1.00x10–6. The Ksp of calcium fluoride is 3.90x10–11. What is the remaining concentration of the first ion to precipitate when the second ion begins to precipitate?
A solution is 0.10 M Pb(NO3)2 and 0.10 M AgNO3. If solid NaCl is added to...
A solution is 0.10 M Pb(NO3)2 and 0.10 M AgNO3. If solid NaCl is added to the solution, what is [Ag+] when PbCl2 begins to precipitate? (Ksp PbCl2 = 1.7 x 10-5; AgCl = 1.8 x 10-10)
Sodium phosphate is added to a solution that contains 0.0077 M aluminum nitrate and 0.031 M...
Sodium phosphate is added to a solution that contains 0.0077 M aluminum nitrate and 0.031 M calcium chloride. The concentration of the first ion to precipitate (either Al3+ or Ca2+) decreases as its precipitate forms. What is the concentration of this ion when the second ion begins to precipitate?
Sodium phosphate is added to a solution that contains 0.0099 M aluminum nitrate and 0.021 M...
Sodium phosphate is added to a solution that contains 0.0099 M aluminum nitrate and 0.021 M calcium chloride. The concentration of the first ion to precipitate (either Al3+ or Ca2+) decreases as its precipitate forms. What is the concentration of this ion when the second ion begins to precipitate?
A 75 L solution of 0.63 M Fe(NO3)3 is mixed with 89 mL of 0.33 M...
A 75 L solution of 0.63 M Fe(NO3)3 is mixed with 89 mL of 0.33 M Ni(NO3)2. Ksp Fe(OH)3=1.63x10^-39 and Ksp Ni(OH)2 = 6x10^-16 (a) If solid KOH is added to the solution, what will precipitate first? Give the chemical formula. (b) If solid KOH is added to the solution, at what concentration of [OH-] will one begin to see the first sign of precipitate? (c) At what concentration of [OH-] will one begin to see the first sign of...
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?
ADVERTISEMENT
Need Online Homework Help?

Get Answers For Free
Most questions answered within 1 hours.

Ask a Question
ADVERTISEMENT