i feel like none of these answers are right.
if the solubility of the solid is 'S' mol/ L, what is the Ksp of the product of the salt?
Ca3PO42-(s) --> 3Ca2+(aq) + 2PO42- (aq)
A)ksp=S^2
B)ksp=4S^3
C)ksp=27S^4
D)ksp=108S^5
Only leaning towards D because its the only one that makes sense...
ksp=[3Ca2+]^3[2PO42-]^2 ????
ksp=108S^5
D is right BUT you have a SERIOUS error in what you wrote. Ksp expression is not what you wrote.
Ksp = (Ca^2+)^3*(PO4^3-)^2. Note that you don't have that. Here is the problem.
Ca3PO4 ==> 3Ca^2+ + 2PO4^3-
I...........0........0
C...........3S.......2S
E..........3S........2S
So Ksp = what I wrote above.
Ksp = (3S)^3(2S)^2 = 108S^5
Note that if you try it your way it is
(3*3S)^3(2*2S)^2 = not 108S^5
To find the equilibrium constant expression for the dissolution of the salt, you need to consider the balanced equation:
Ca3PO42-(s) --> 3Ca2+(aq) + 2PO42-(aq)
The general form of the equilibrium constant expression (Ksp) for a solid dissociating into ions in solution is:
Ksp = [Ca2+]^m [PO42-]^n
In this case, the stoichiometric coefficients of Ca2+ and PO42- in the balanced equation are 3 and 2 respectively. So, m = 3 and n = 2.
Now, let's consider the given options:
A) ksp = S^2
This option assumes a 1:1 mole ratio between the solid and its ions, which is not the case here. Therefore, this option is incorrect.
B) ksp = 4S^3
This option assumes that m = 4 and n = 3, which is not correct for this balanced equation. Therefore, this option is incorrect.
C) ksp = 27S^4
This option assumes that m = 27 and n = 4, which is also not correct for this balanced equation. Therefore, this option is incorrect.
D) ksp = 108S^5
This option assumes that m = 108 and n = 5, which is not correct for this balanced equation. Therefore, this option is also incorrect.
From our analysis, none of the given options are correct. Therefore, you should consider alternative options or reevaluate the problem.