Question

Two compounds with general formulas A2X and AX3 have Ksp=1.5×10−5M. Part A Which of the compounds has the higher molar solubility? Which of the compounds has the higher molar solubility? A2X AX3

Answer 1

Hey there!:

To get to the molar solubility from the Ksp, you have to think about the how Ksp is calculated, and what it means.  

For a compound that forms 2 ions, Ksp = X^2 where X is the molar solubility. For a compound that forms 3 ions, Ksp = 4X^3, where again, X is the molar solubility.  

If you calculate the molar solubilities of each of your compounds, you will see that  A2X  has the higher molar solubilty

Hope this helps!

Answer 2

Answer:

A₃X

Explanation:

In order to find the molar solubility (S) of a compound, we will use an ICE Chart.

A₂X

Let's consider the solution of A₂X.

     A₂X(s) ⇄ 2 A⁺(aq) + X²⁻(aq)

I                         0           0

C                     +2S        +S

E                       2S          S

The solubility product (Kps) is:

Kps = 1.5 × 10⁻⁵ = [A⁺]².[X²⁻] = (2S)².S = 4S³

S = 0.016 M

A₃X

Let's consider the solution of A₃X.

     A₃X ⇄ 3 A⁺(aq) + X³⁻(aq)

I                    0             0

C                 +3S         +S

E                   3S           S

The solubility product (Kps) is:

Kps = 1.5 × 10⁻⁵ = [A⁺]³.[X³⁻] = (3S)³.S = 27 S⁴

S = 0.027 M

A₃X has a higher molar solubility than A₂X.