Question

Give the equilibria and the solubility product expressions for the following: a. BaSO4 b. Fe(OH)3 c. Ca3(PO4)2

Answer 1

a. BaSO4

    BaSO4 (s) <-----> Ba+2(aq) + SO4^-2(aq)

   K = [Ba+2][SO4^-2] / [BaSO4]

K* [BaSO4]    = [Ba+2][SO4^-2]

K* [BaSO4]   = Ksp

Ksp = [Ba+2][SO4^-2]

b. Fe(OH)3

Fe(OH)3 (s) <------> Fe+3(aq) + 3 OH-(aq)

K = [Fe+3][OH-]^3/[Fe(OH)3]

K*[Fe(OH)3] = [Fe+3][OH-]^3

Ksp = [Fe+3][OH-]^3

c. Ca3(PO4)2

Ca3(PO4)2 (s) <------> 3Ca+2(aq) +2 PO4^-3(aq)

K = [Ca+2]^3[PO4^-3]^2/[Ca3(PO4)2 ]

K*[Ca3(PO4)2 ] = [Ca+2]^3[PO4^-3]^2

K*[Ca3(PO4)2 ] = Ksp

Ksp = [Ca+2]^3[PO4^-3]^2