Chemical reactions

Reaction of silver with acids

Silver metal dissolves in hot concentrated sulphuric acid.

Silver dissolves in dilute nitric acid, HNO3 [8].

3 Ag(s) + 4 HNO3(aq) AgNO3(aq) + NO(g) + 2 H2O(l)

Reaction of silver with air

Silver metal is stable in clean air under normal conditions.

Reaction of silver with ammonia

Ammonia precipitates Ag+ as brown/black oxide.

2 Ag+(aq) + 2 NH3(aq) + H2O(l) Ag2O(s) [brown/black] + 2 NH4+(aq)

In excess, ammonia dissolves the precipitate, forming a diamine silver complex.

Ag2O(s) + 4 NH3(aq) + H2O(l) 2 [Ag(NH3)2]+(aq) + 2 OH(aq)

Reaction of silver with cyanide

Ag+ forms complexes with cyanide [8].

Ag+(aq) + 2 CN(aq) [Ag(CN)2](aq)

The complex is used for extration of silver in solid form, where the reaction is [8]:

4 Ag(s) + 8 CN(aq) + O2(g) + 2 H2O(l) 4 [Ag(CN)2](aq) + 4 OH(aq)

Reaction of silver with halides

Ag+ is precipitated by halides. The precipitates can be dissolved again in concentrated halides.

Ag+(aq) + Cl(aq) AgCl(s) [white]
AgCl(s) + Cl(aq) [AgCl2](aq) + Cl(aq) [AgCl3]2−(aq) + Cl(aq) [AgCl4]3−(aq)

Ag+(aq) + Br(aq) AgBr(s) [light yellow]
AgBr(s) + Br(aq) [AgBr2](aq) + Br(aq) [AgBr3]2−(aq) + Br(aq) [AgBr4]3−(aq)

Ag+(aq) + I(aq) AgI(s) [yellow]
AgI(s) + I(aq) [AgI2](aq) + I(aq) [AgI3]2−(aq) + I(aq) [AgI4]3−(aq)

Reaction of silver with hydroxide

Hydroxide ions precipitates Ag+ as brown/black oxide.

2 Ag+(aq) + 2 OH(aq) Ag2O(s) [brown/black] + H2O(l)

Reaction of silver with sulfide

Silver reacts with hydrogen sulfide in the presence of oxygen [8]:

4 Ag(s) + 2 H2S(g) + O2(g) Ag2S(s) + 2 H2O(l)

Ag+ is precipitated by hydrogensulfide in 0.4M HNO3(aq):

2 Ag+(aq) + H2S(aq) Ag2S(s) [black] + 2 H+(aq)

Reaction of silver with the thiosulfate

Ag+ forms complexes with thiosulfate.

Ag+(aq) + 2 S2O32−(aq) Ag(S2O3)23−(aq)

The process is used for removing AgBr(s) in photographic fixing.

Reaction of silver with water

Silver does not react with clean water.

Quantitative analysis

Method 3500-Ag C Inductively Coupled Plasma Method [2]. A portion of the sample is digested in a combination of acids. The digest is aspirated into an 8,000 K argon plasma where resulting light emission is quantified for 30 elements simultaneously.

Method limit of detection in water = 0.003 mg/L
Method limit of detection in soil = 0.10 mg/kg