Question

What happens when excees of naoh is added to agcl

Answer 1

ANSWER:

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Contributed by James P. Birk

Professor Emeritus (Chemistry) at Arizona State University

Most common oxidation state: +1

M.P. 961º

B.P. 2210º

Density 10.49 g/cm3

Characteristics: Silver is a inactive metal. It will react with hot concentrated H2SO4 , with HNO3 , and with aqua regia.

Characteristic reactions of Ag+ :

Chloride Ion

Soluble chlorides, such as hydrochloric acid, precipitate silver ion as white silver(I) chloride.

Ag+(aq)+Cl−(aq)↽−−⇀AgCl(s)(1)

Ag1ppt.gif

Silver(I) chloride is insoluble in acids, including HNO3 . The precipitate does dissolve in aqueous ammonia:

AgCl(s)+2NH3(aq)↽−−⇀[Ag(NH3)2]+(aq)+Cl−(aq)(2)

Sr5b2.gif

Addition of an acid to this solution, such as HNO3 , destroys the complex ion and re-precipitates silver(I) chloride:

[Ag(NH3)2]+(aq)+Cl−(aq)+2H+(aq)↽−−⇀AgCl(s)+2NH+4(aq)(3)

Ag1ppt.gif

Sulfate Ion

No reaction occurs on addition of sulfate ion unless the concentration of Ag+ is high, in which case silver(I) sulfate precipitates.

Aqueous Ammonia

Aqueous ammonia precipitates brown Ag2O :

2Ag+(aq)+2NH3(aq)+2H2O(l)↽−−⇀Ag2O(s)+2NH+4(aq)+H2O(l)(4)

Ag4ppt.gif

The silver(I) oxide precipitate dissolves in excess ammonia to form a colorless complex ion:

Ag2O(s)+4NH3(aq)+H2O(l)↽−−⇀2[Ag(NH3)2]+(aq)+2OH−(aq)(5)

Bi5appt.gif

Sodium Hydroxide

Sodium hydroxide precipitates silver(I) oxide:

2Ag+(aq)+2OH−(aq)↽−−⇀Ag2O(s)+H2O(l)(6)

Ag4ppt.gif

Silver(I) oxide does not dissolve in excess NaOH .