Question

Hw5B-Chapter17 Problem 17.73 8 of 14 > Constants| Periodic T Part A Review able A solution contains 2.0x10 4 M Ag+ and 1.5x10 3 M Pb2 lf Nal is added, will Agl (K, 8.3 x 10 ") or P112 (K,-7.9 x 10。) precipitate frst? AgI will precipitate first Pb12 will precipitate first Previous Answers Correct Part B Specify the concentration of I needed to begin precipitatian. Express your answer using two significant figures Submit Request Answer

Answer 1

Part A: As given in the question, AgI has a lower solubility product (Ksp) value than that of PbI₂. This means it has low solubility in water as compared to PbI_2. As a result AgI will precipitate first.

Part B. As discussed above, AgI will precipitate first because of its low Ksp value.

Ksp of AgI=8.3x10^-17

Given concentration of Ag⁺ ions in solution=[Ag⁺]=2.0x10¹ M

Equation for solubility of AgI in water

$AgI(s)+H_2O(l)\rightleftharpoons Ag^+(aq)+I^-(aq)$

Ksp=[Ag⁺][I^-]=8.3x10^-17

2.0x10¹ x [I^-]=8.3x10^-17

[I^-]=8.3x10^-17/2.0x10¹=4.15x10^-18 M

So concentration of I^- needed to begin precipitation=4.15x10^{​​​​​​-18} M$\approx$4.2x10^-18 M