Question

For each of the salts on the left, match the salts on the right that can be compared directly, using Ksp 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. magnesium hydroxide A. CuCO3

2. lead carbonate B. Pb(OH)2

C. Mn(OH)2

D. CaS

Write the expression for K in terms of the solubility, s, for each salt, when dissolved in water. magnesium hydroxide lead carbonate Ksp = Ksp = Note: Multiply out any number and put it first in the Ksp expression. Combine all exponents for s.

1 & 2 COULD HAVE MORE THAN ONE ANSWER

Answer 1

Ksp for Mg(OH)2

Mg(OH)2 -> Mg+ 2 OH-

s 2s  

Ksp for Mg(OH)2=s*(2s)^2=4*s^3

Ksp for PbCO3

PbCO3 -> Pb+ CO3

s s  

Ksp for PbCO3=s*(s)=s^2

Ksp for CaS

CaS -> Ca+ S

s s  

Ksp for CaS=s*(s)=s^2

Ksp for CuCO3

CuCO3 -> Cu+ CO3

s s  

Ksp for CuCO3=s*(s)=s^2

Ksp for Pb(OH)2

Pb(OH)2 -> Pb+ 2 OH-

s 2s  

Ksp for Pb(OH)2=s*(2s)^2=4*s^3

Ksp for Mn(OH)2

Mn(OH)2 -> Mn+ 2 OH-

s 2s  

Ksp for Mn(OH)2=s*(2s)^2=4*s^3

From all these calculations we can see that

Ksp Mg(OH)2=Pb(OH)2,Mn(OH)2

Ksp PbCO3= CuCO3,CaS

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