Which of the following hydrogen halides react(s) with AgNO3(aq) to give a precipitate that dissolves in Na2S2O3 (aq) ?
AgF is soluble in water
AgNO3 + HX (X = Cl, Br, I) AgX ¯ [Ag(S2O3)2]–3 (soluble)
This question involves understanding the reactivity of hydrogen halides with silver nitrate and the solubility of their precipitates in sodium thiosulfate solution. Let's break it down step by step.
Hydrogen halides (HX) react with AgNO3 to form silver halide precipitates (AgX):
AgCl, AgBr, and AgI are insoluble and form precipitates, while AgF is soluble and does not precipitate.
Sodium thiosulfate (Na2S2O3) dissolves certain silver halides by forming soluble complexes:
AgBr and AgI dissolve in Na2S2O3, but AgCl does not; it dissolves in ammonia instead.
HBr and HI react with AgNO3(aq) to give precipitates that dissolve in Na2S2O3(aq).
Solubility Rules: AgCl, AgBr, AgI are insoluble; AgF is soluble.
Complex Formation: AgBr and AgI form soluble complexes with thiosulfate:
Key Concept: The ability of silver halides to dissolve in complexing agents like thiosulfate or ammonia depends on the stability of the complex formed, which varies with the halide ion.