A solution is 0.1M in Cl- and 0.1M in CrO4-- ions. If solid AgNO3 is gradually added to this solution which one will precipitate first? At what concentration of Cl-, Ag2CrO4 starts precipitating? (Ksp of AgCl= 1.7x10-19, Ksp of Ag2CrO4 = 1.9x10-12).

SAGAR SINGH - IIT DELHI
879 Points
12 years ago

Dear student,

• Solubility Product, Ksp, refers to an ionic compound dissolving to form ions
• For the reaction: MA(s) M+(aq) + A-(aq)

The equilibrium constant K is:

 K = [M+][A-] [MA]

• Since the concentration of the solid is a constant, it is effectively incorporated into the equilibrium constant: Ksp = [M+][A-]
• [M+][A-] is referred to as the ion product.
• At equilibrium, the ion product = solubility product (Ksp) and the solution is said to be saturated.
• A precipitate will form when two solutions are mixed if the ion product is greater than the solubility product, ie, [M+][A-] > Ksp

All the best.

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Sagar Singh

B.Tech, IIT Delhi