Question

For each of the salts on the left, match the salts on the right that can be compared directly, using K_sp values, to estimate solubilities.

(If more than one salt on the right can be directly compared, include all the relevant salts by writing your answer as a string of characters without punctuation, e.g, ABC.)

	1.	_____ silver chromate		A. Ag3PO4
	2.	_____ iron(III) hydroxide		B. Zn3(PO4)2
				C. Ni(OH)2
				D. BaF2

******The first part above can have more than one answer (example A,B) ****

Please only answer this if you are 100% confident as I am down to my last attempt... Thanks!

Write the expression for K in terms of the solubility, s, for each salt, when dissolved in water.

silver chromate			iron(III) hydroxide
Ksp = ____			Ksp = ____

Note: Multiply out any number and put it first in the K_sp expression. Combine all exponents for s.

Answer 1

Recal that

Ksp = [A]^a[B]^b

for

Silver chromate --> Ag2CrO4 --> 2Ag+ + CrO4-2 --> type 2A + B

Ag3PO4 = 3A + B

Zn3(PO4)2 --> 3A + 2B

Ni(OH)2 --> A + 2B

BaF2 --> A + 2B

note that 2A + B <-> A + 2B

so

silver chromate can be compared directy with Ni(OH)2 and BaF2

Q2.

for Iron III hydroxide --> Fe(OH)3 --> Fe+3 + 3OH- --> A + 3B type

so

Ag3PO4 = 3A + B

Zn3(PO4)2 --> 3A + 2B

3A + B <-> A + 3B

only Ag3P4 can be compared

Q3.

K in terms f "S" for each salt:

Ag2CrO4 --> 2Ag+ + CrO4-2

Ksp = [Ag+]^2[CrO4-2]

Let S be 1 mol of salt so

[Ag+] = 2S and CrO4-2 = S

Ksp = (2S)^2(S)

Ksp = 4S^3

Fe(OH)3 --> Fe+3 + 3OH-

Ksp = [Fe+3][OH-]^3

1 mol of salt = S

Fe+3 = S

OH- = 3S

Ksp = (S)(3S)^3

Ksp = 27S^4