What is the maximum concentration of Ag⁺ that can be added to a 0.00640 M solution of Na₂CO₃ before a precipitate will form? (Ksp for Ag₂CO₃ is 8.10 × 10⁻¹²)

Question

What is the maximum concentration of Ag⁺ that can be added to a 0.00640 M solution of Na₂CO₃ before a precipitate will form? (Ksp for Ag₂CO₃ is 8.10 × 10⁻¹²)

Answer 1

Do an ICE table to determine the concentration of Ag⁺ added in order to just form a precipitate

The K_SP expression is [Ag⁺]² [CO₃^2-] which is equal to 8.1 x 10^-12 at equilibrium.

Assuming x is the concentration of Ag⁺ needed to lead to a ppt:

[Ag⁺]_eq = x

[CO₃^2-]_eq = .0064 M from original solution of sodium carbonate

.0064x² = 8.1 x 10^-12

Solve for x. ( I get 3.6 x 10^-5 M)

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