multiple choice chem?

A.
AgCl(s) ⇌ Ag⁺(aq) + Cl⁻(aq) …. Ksp = 1.77 × 10⁻¹⁰
Reaction quotient, Qc = [Ag⁺] [Cl⁻] = (5.0 × 10⁻⁵)² = 2.5 × 10⁻⁹ > Ksp
Hence, AgCl precipitate will form.

B.
Ag₂SO₄(s) ⇌ 2Ag⁺(aq) + SO₄²⁻(aq) … Ksp = 1.12 ×10⁻⁵
Reaction quotient, Qc = [Ag⁺]² [SO₄²⁻] = (5.0 × 10⁻⁵)³ = 1.25× 10⁻¹³ < Ksp
Hence, Ag₂SO₄ precipitate will NOT form.

C.
Ag₂CO₃(s) ⇌ 2Ag⁺(aq) + CO₃²⁻(aq) … Ksp = 8.46 ×10⁻¹²
Reaction quotient, Qc = [Ag⁺]² [CO₃²⁻] = (5.0 × 10⁻⁵)³ = 1.25× 10⁻¹³ < Ksp
Hence, Ag₂CO₃ precipitate will NOT form.

The answer: A. AgCl

Calculate the K for each compound using the concentrations given.  If K > Ksp, a precipitate forms.  So for AgCl, you have K = 5.0×10−5 M * 5.0×10−5 M = 2.5 * 10^-9.  this is greater than 1.77 × 10–10 so you get a precipitate.