Question

Iculate the molar solubility of MX (Ksp = 1.27 x 10-36) in: 68. Calculate the molars a. pure water b. 0.25 M MCI, c. 0.20 M Na X lata tha molar cal..

Answer 1

a)

At equilibrium:
MX        <---->     M2+      +          X2-    

                     s                  s       

Ksp = [M2+][X2-]
1.27*10^-36=(s)*(s)
1.27*10^-36= 1(s)^2
s = 1.127*10^-18 M
Answer: 1.13*10^-18 M

b)
MCl2 here is Strong electrolyte
It will dissociate completely to give [M2+] = 0.25 M
At equilibrium:
MX        <---->     M2+      +          X2-    
                     0.25 +s            s       
Ksp = [M2+][X2-]
1.27*10^-36=(0.25 + s)*(s)
Since Ksp is small, s can be ignored as compared to 0.25
Above expression thus becomes:
1.27*10^-36=(0.25)*(s)
1.27*10^-36= 0.25 * 1(s)^1
s = 5.08*10^-36 M
Answer: 5.08*10^-36 M

c)

Na2X here is Strong electrolyte
It will dissociate completely to give [X2-] = 0.2 M
At equilibrium:
MX        <---->     M2+      +          X2-    
                     s                  0.2 + s
Ksp = [M2+][X2-]
1.27*10^-36=(s)*(0.2+ s)
Since Ksp is small, s can be ignored as compared to 0.2
Above expression thus becomes:
1.27*10^-36=(s)*(0.2)
1.27*10^-36= (s) * 0.2
s = 6.35*10^-36 M
Answer: 6.35*10^-36 M