Equal volumes of 0.020 M Ag⁺(aq)solution and 2.0 M NH₃(aq)solution are mixed.K_f for [Ag(NH₃)₂]⁺ is 1.6 × 10⁷.If trisodium arsenate is added so that the arsenate ion concentration is 0.10 M,will silver arsenate precipitate? What is Q_sp? K_sp for silver arsenate is 1.0 × 10^-22.

Question

Quizplus · Accepted Answer

Given the K_sp for silver arsenate is significantly lower (1.0 × 10^-22) than the calculated Q_sp (which would be a result of the product of the concentrations of Ag+ and arsenate ions), and since the calculated Q_sp is much higher than K_sp, it would seem that silver arsenate should precipitate. However, the presence of a complexing agent (NH₃) can significantly increase the solubility of Ag+ ions, preventing the precipitation of silver arsenate. The correct answer must account for the complexation effect, which is not directly provided in the question, leading to a misunderstanding in the explanation. The correct approach involves calculating the actual concentration of free Ag+ ions in the presence of the complexing agent and arsenate, but without specific calculations or the effect of the complexing agent detailed in the options, the answer choice based on the provided information was incorrect. The correct answer should involve understanding that the presence of a strong complexing agent and the given conditions might not lead to precipitation, but the specific Q_sp calculation and comparison to K_sp are crucial for a definitive conclusion.

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