Suppose the molar solubility of Ag2CrO4 in water is x M, while its molar solubility in a 0.005 M solution of Na2CrO4 is y M. Which of the following is correct?

Question

Suppose the molar solubility of Ag2CrO4 in water is x M, while its molar solubility in a 0.005 M solution of Na2CrO4 is y M. Which of the following is correct?

  It can't be determined.

  x > y

  x < y

  x = y

 

Answer 1

This is an example of the common ion effect, with CrO₄^2- being the common ion.

According to Le Chatelier, the presence of the common ion will push the reaction toward the left (insoluble salt) making the solubility less than what it is in water.

Thus, x > y

Ag₂CrO₄(s) ==> 2Ag⁺(aq) + CrO₄^2-(aq)

Adding CrO₄^2-will push the reaction to the left, making the salt less soluble than if CrO₄^2- was absent.