Silver

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)

Silver metal is stable in clean air under normal conditions.

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)

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)

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)

Hydroxide ions precipitates Ag⁺ as brown/black oxide.

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

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)

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.

Silver does not react with clean water.

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