Question

Nine\

Compound	Formula	Ksp
Iron(II) sulfide	FeS	3.72x10-19
Magnesium hydroxide	Mg(OH)2	2.06x10-13
Calcium fluoride	CaF2	1.46x10-10

Part A Use the ksp values in the table to calculate the molar solubility of FeS in pure water?

Part B Use the Ksp values in the table to calcualte the molar solubility of Mg(OH)₂ in pure water.?

Part C Use the Ksp values in the table to calculate the molar solubilty of CaF₂ in pure water.?

Answer 1

A)

The salt dissolves as:

FeS <----> Fe2+ + S2-

   s s

Ksp = [Fe2+][S2-]

3.72*10^-19=(s)*(s)

3.72*10^-19= 1(s)^2

s = 6.099*10^-10 M

Answer: 6.10*10^-10 M

B)

The salt dissolves as:

Mg(OH)2 <----> Mg2+ + 2 OH-

   s 2s

Ksp = [Mg2+][OH-]^2

2.06*10^-13=(s)*(2s)^2

2.06*10^-13= 4(s)^3

s = 3.721*10^-5 M

Answer: 3.72*10^-5 M

C)

The salt dissolves as:

CaF2 <----> Ca2+ + 2 F-

   s 2s

Ksp = [Ca2+][F-]^2

1.46*10^-10=(s)*(2s)^2

1.46*10^-10= 4(s)^3

s = 3.317*10^-4 M

Answer: 3.32*10^-4 M