[bblue]

Rank the following five salts in order of decreasing solubility, in terms of mass per unit volume.
(The most soluble gets rank 1, the least soluble gets rank 5.)

Ag3PO4     (Ksp = 1.80×10-18)
Ag2CrO4     (Ksp = 9.00×10-12)
Ca5(PO4)3F     (Ksp = 1.00×10-60)
Ca3(PO4)2     (Ksp = 1.30×10-32)
AgCl     (Ksp = 1.60×10-10)

So here is my work:

i first found the concentration of the ions:
Ag3PO4 : 1.60685E-5 M
Ag2CrO4 : 1.31037E-4 M
Ca5(PO4)3F : 6.109086E-8 M
Ca3(PO4)2 : 1.644765E-7 M
AgCl : 1.264911E-5 M

Then i used the concentrations and multiplied it by the molar mass and got the following solubilities [g / L]
Ag3PO4 : .0067259 g/L
Ag2CrO4 : .0434687 g/L
Ca5(PO4)3F : 3.0808E-5 g/L
Ca3(PO4)2 : 5.10167E-5 g/L
AgCl : .0081288 g/L

So the salt with the highest solubility would be the salt with the highest number:
3) Ag3PO4
1) Ag2CrO4
5) Ca5(PO4)3F
4) Ca3(PO4)2
2) AgCl

The rank that i have shown is incorrect 
and i dont know why
can someone PLEASE check my work
THANK YOU!!

[Borek]

i first found the concentration of the ions:
Ag3PO4 : 1.60685E-5 M
Ag2CrO4 : 1.31037E-4 M
Ca5(PO4)3F : 6.109086E-8 M
Ca3(PO4)2 : 1.644765E-7 M
AgCl : 1.264911E-5 M

Which ions?

How they are related to the concentration of the salt?

[bblue]

well for the Ag3PO4 salt, this is how i found the concentration:

ksp = [3*x]^3 *

1.80×10-18 = 27(x^4)
x = 1.6E-5 M
x = [PO4]
and it would also equal to the concentration of the salt
wouldn't it?

[Borek]

So far so good. Show how you have dealt with Ca₃(PO₄)₂.

[bblue]

ok well here is my work for Ca3(PO4)2:

1.30E-32 = [3x]^3*[2x]^2
             = 108(x^5)
          x = 1.644765E-7 M
1.644765E-7 M * 310.17672 g = 5.10167E-5 g/L
is my work right?

[Borek]

No.

How many moles of Ca²⁺ per one mole of Ca₃(PO₄)₂?

[bblue]

wouldn't there be 3 moles for every 1 mole of Ca₃(PO₄)₂??

Ca₃(PO₄)₂  3 Ca²⁺ + 2 PO₄^2-

or is this eqn wrong, would Ca²⁺ actually exist as Ca₂²⁺ b/c the charges aren't really making any sense to me
I dont know how they got the 3 on the left side for the Ca

[Borek]

PO₄^3-

Yes, 3 moles of Ca²⁺ per mole of Ca₃(PO₄)₂. Now, if so - what is concentration of Ca₃(PO₄)₂ for a given concentration of Ca²⁺?

[bblue]

i THINK i understand what you are trying to say...

so the concentration i found is actually 3 times more than the concentration of my salt right?
but would i have to divide by 2 or would i have to divide by 3 ??
and what exactly did i find the concentration of ??

[Borek]

Argh, sorry - my mistake. You wrote

i first found the concentration of the ions:

and I was sure you did a classic mistake of not converting between ions/salt concentration, but your x was all the time salt concentration and your approach was correct.

Problem seems to be much simpler. Check your math for AgCl.

[bblue]

i did the problem again and i got the same results...

AgCl  Cl^- + Ag⁺

1.60E-10 =

1.60E-10 = x^2
x = 1.264911E-5 M

1.264911E-5 M * 143.321 g = .008128832 g/L

is there anything else that could be wrong with my calculations?

[Borek]

1.264911E-5 M * 143.321 g = .008128832 g/L

Check it again.

[killer120]

Rank the following five salts in order of decreasing solubility, in terms of mass per unit volume.
(The most soluble gets rank 1, the least soluble gets rank 5.)

Ag3PO4     (Ksp = 1.80×10-18)
Ag2CrO4     (Ksp = 9.00×10-12)
Ca5(PO4)3F     (Ksp = 1.00×10-60)
Ca3(PO4)2     (Ksp = 1.30×10-32)
AgCl     (Ksp = 1.60×10-10)

So here is my work:

i first found the concentration of the ions:
Ag3PO4 : 1.60685E-5 M
Ag2CrO4 : 1.31037E-4 M
Ca5(PO4)3F : 6.109086E-8 M
Ca3(PO4)2 : 1.644765E-7 M
AgCl : 1.264911E-5 M

Then i used the concentrations and multiplied it by the molar mass and got the following solubilities [g / L]
Ag3PO4 : .0067259 g/L
Ag2CrO4 : .0434687 g/L
Ca5(PO4)3F : 3.0808E-5 g/L
Ca3(PO4)2 : 5.10167E-5 g/L
AgCl : .0081288 g/L

So the salt with the highest solubility would be the salt with the highest number:
3) Ag3PO4
1) Ag2CrO4
5) Ca5(PO4)3F
4) Ca3(PO4)2
2) AgCl

The rank that i have shown is incorrect 
and i dont know why
can someone PLEASE check my work
THANK YOU!!

hello....I'm a new member here!nice to meet you all!
i think the ranking is suppose like this :-
3) Ag3PO4
2) Ag2CrO4
5) Ca5(PO4)3F
4) Ca3(PO4)2
1) AgCl
is this the correct answer?
i think if we are trying to arrange the solubility of few salts,we should just compare the Ksp of the salts only,we are not suppose to calculate the concentration of each ion which exists in the salt.So,i think those equation is not necessary..
anyway,that's my opinion on the question.....i hope i can help someone there by reply this post!

[Borek]

i think if we are trying to arrange the solubility of few salts,we should just compare the Ksp of the salts only

Salt XY has solubility 0.01M - what is its K_sp?

Salt X₂Y₃ has 5 times higher solubility of 0.05M - what is its K_sp?

If you compare K_sp of both salts, will you get result telling you that second salt has greater solubility?

[killer120]

i think if we are trying to arrange the solubility of few salts,we should just compare the Ksp of the salts only

Salt XY has solubility 0.01M - what is its K_sp?

Salt X₂Y₃ has 5 times higher solubility of 0.05M - what is its K_sp?

If you compare K_sp of both salts, will you get result telling you that second salt has greater solubility?

i already calculate the question you give me....OK below is my answer for your question :-
the K_sp for salt XY is [0.01][0.01]=0.0001M^-2
the K_sp for salt X₂Y₃ is [2(0.05)]²[3(0.05)]³=0.00003375M^-5

so,in the end the K_sp of salt XY is higher than K_sp for salt X₂Y₃ then i can know that salt XY is more soluble than salt X₂Y₃.
Am i right?
thanks for solving my misunderstanding during i learning this topic.....thank you again!now i know my mistake!