Question

a. The K_sp for Ag₂SO₃ = 1.50 X 10^-14. What is the molar solubility of Ag₂SO₃ in a 5 M solution of lithium sulfite?

b.The K_sp for Mg₃(PO₄)₂ = 1.04 X 10^-24. What is the molar solubility of Mg₃(PO₄)₂ in a 1.40 M solution of sodium phosphate?

c.If the Ksp for Y(OH)₃ = 1.00 X 10^-22, what is the molar solubility of Y(OH)₃ in a buffer solution composed of 1.60M trimethylamine (= (CH₃)₃N) (K_b = 6.5 X 10^-5) and 1.40M trimethylaminium hydrochloride (= (CH₃)₃NH⁺Cl^-)?

Answer 1

Q1.

Ksp = [Ag+]^2[SO3-2]

1.5*10^-14 = (2S)^2 * (5)

S = ((1.5*10^-14)/20)^0.5

s = 2.738*10^-8 M;

Q2.

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

let S = moalr solubility of Mg3(PO4)2

[Mg+2] = 3S

[PO4-3] = 2S

substitute in Ksp

(1.04*10^-24) = (3S)^3 * (2S)^2

108*S^5 = (1.04*10^-24)

S = ((1.04*10^-24)/108 )^(1/5)

S = 0.000006262 M for Mg3(PO4)2

Q3

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

given bufer

pOH = pKb + log(Bh+/B)

pKb = -log(Kb) = -log(6.5*10^-5) = 4.1870

pOH = 4.1870 + log(1.4/1.4)

pOH = 4.1870

[Oh-] = 10^-pOH = 10^-4.1870 = 6.5*10^-5

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

10^-22 = S*( 6.5*10^-5)^3

S = (10^-22)/(( 6.5*10^-5)^3)

S = 3.6413*10^-10 M