Question

For each of the salts on the left, match the salts on the right that can be compared directly, using Kp 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 iodide 2. magnesium fluoride A. Pb(OH)2 B. Zn(CN)2 C. CaSO4 D. PbCO3 Write the expression for K in terms of the solubility, s, for each salt, when dissolved in water. silver iodide magnesium fluoride Ksp = Note: Multiply out any number and put it first in the Ksp expression. Combine all exponents for s.

Answer 1

1. Silver iodide (AgI) :- CD (CaSO₄ PbCO₃)

2. Magnesium fluoride (MgF₂) :- AB (Pb(OH)₂ Zn(CN)₂)

Explanation :-

1) The solubility equilibrium for AgI is

AgI() = AgTag) + Ting

And the solubility product is

Ksp = [Ag+][T]

We can compare AgI salt directly using K_sp with CaSO₄ and PbCO₃ salts as,

a) The solubilty equilibrium for CaSO₄ is

CaSO4(s) = Caldo + so (aq)

And the solubility product is  

Ksp = [Ca²+1[S02-

b) The solubilty equilibrium for PbCO₃ is

PbCO3(s) = Pb) + Co (aq)

And the solubility product is

Ksp = [Pb2+][CO-

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2) The solubility equilibrium for MgF₂ is

MgF2(8) = M974) + 2F

And the solubility product is

Ksp = [Mg2+][F-14

we can compare MgF₂ salt directly using K_sp with Pb(OH)₂ and Zn(CN)₂ as,

a) The solubilty equilibrium for Pb(OH)₂ is

Pb(OH)2() = P67 + 20

And the solubility product is

Ksp = [Pb2+][OH-]

b) The solubilty equilibrium for Zn(CN)₂ is

Zn(CN)2(s) = Zn2+ + 2C NGO

And the solubility product is

Ksp = [Zn2+][CN-]

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Expression for K in term of solubility 's'

we have,
AgI() = AgTag) + Ting
....(A)

and
Ksp = [Ag+][T]

From equilibrium (A), if [Ag⁺] = s then [I^-] = s

therefore,
Kp = SXS =
  

Again

we have,
MgF2(8) = M974) + 2F
....(B)

and   
Ksp = [Mg2+][F-14

From equilibrium (B), if [Mg⁺] = s then [F^-] = 2s

Therefore,   
Ksp = 5 x 2s) = 8 x 45+ = 45