Question

AgNO3 is slowly added to an aqueous solution containing 0.02 M AsO43-, 0.02 M I- and 0.02 M CO32-. In what order would the silver salts precipitate?Ksp( Ag3AsO4)= 1.0 x 10-22Ksp (AgI) = 8.3 x 10-17Ksp (Ag2CO3)= 8.1 x 10-12Ag2CO3, AgI, Ag3AsO4Ag3AsO4, Ag2CO3, AgIAg2CO3, Ag3AsO4, AgIAg3AsO4, AgI, Ag2CO3AgI , Ag3AsO4, Ag2CO3

Answer 1

The first silver salt in precipitate is Ag₃AsO₄, then AgI and, in the last, Ag₂CO₃

Step-by-step explanation:

The Ksp equilibrium for Ag₃AsO₄ is:

Ag₃AsO₄ ⇄ 3 Ag⁺ + AsO₄³⁻

ksp = 1,0 x 10⁻²² = [Ag⁺]³ [AsO₄³⁻]

For AgI is:

AgI ⇄ Ag⁺ + I⁻

ksp = 8,3 x 10⁻¹⁷ = [Ag⁺] [I⁻]

And for Ag₂CO₃ is:

Ag₂CO₃ ⇄ 2 Ag⁺ + CO₃²⁻

ksp = 8,1 x 10⁻¹² = [Ag⁺]² [CO₃²⁻]

A low ksp value means that ions concentration is low doing salt concentration high. In other words, the lower ksp value, the first in precipitate.

Thus, the first silver salt in precipitate is Ag₃AsO₄, then AgI and, in the last, Ag₂CO₃

I hope it helps!