What is the k for the overall reaction complex

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Unformatted text preview: for Complex formation when NH3 is present in the solution [Ag(NH 3 ) 2 ]+ • Effectively, the Ag+(aq) has been removed from solution. • What is the K for the overall reaction? Complex Formation Constant Kf AgCl ( s ) + − Ag (aq ) + Cl (aq ) Ag + (aq ) + 2 NH 3 (aq ) K sp [ Ag ( NH 3 ) 2 ]+ (aq ) K f The net process: AgCl ( s ) + 2 NH 3 (aq ) [ Ag ( NH 3 ) 2 ]+ ( aq ) + Cl − (aq ) K + − [ Ag ( NH 3 ) 2 ] [Cl ] [ Ag + ] K= ⋅ 2 [ NH 3 ] [ Ag + ] [ Ag ( NH 3 ) 2 ]+ [Cl − ] ⋅ [ Ag + ] = [ NH 3 ]2 ⋅ [ Ag + ] = K f ⋅ K sp = (1.7 ×107 ) × (1.8 ×10−10 ) = 3.1× 10−3 >> 1.8x10-10 (Ksp of AgCl) Exercise: Exercise: Calculate the solubility of AgCl in 1.0 M NH3 aqueous solution. aqueous Ag + (aq ) + Cl − (aq ) AgCl ( s ) Ag + (aq ) + 2 NH 3 (aq ) AgCl ( s ) + 2 NH 3 (aq ) s [ Ag ( NH 3 ) 2 ]+ (aq ) K f [ Ag ( NH 3 ) 2 ]+ (aq ) + Cl − (aq ) 1.0-2s s s [ Ag ( NH 3 ) 2 ]+ [Cl − ] s×s K= = [ NH 3 ]2 (1.0 − 2 s ) 2 ≈ s×s = K f K sp = 3.1× 10−3 1.02 s = 0.056 M K sp Will the solubility of AgCl(s) increase increase or decrease when drops of 1.0 M HNO3 is added? AgCl ( s ) + 2 NH 3 ( aq) [ Ag ( NH 3 ) 2 ]+ (aq ) + Cl − (aq ) + 1.3×10-5M in pure water + 2HNO3 (aq ) → 2 NH 4 (aq ) + 2 NO3− (aq ) AgCl(s) AgCl(s) is less soluble! Colorless Colorless Soln. Colorless...
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This document was uploaded on 02/26/2014.

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