Chemical elements
  Silver
    Isotopes
    Energy
    Production
    Application
    Physical Properties
    Chemical Properties
      Silver fluoride
      Silver subfluoride
      Silver chloride
      Silver subchloride
      Photohalides
      Silver bromide
      Silver oxybromide
      Silver subbromide
      Silver iodide
      Silver hypochlorite
      Silver chlorite
      Silver chlorate
      Silver perchlorate
      Silver bromate
      Silver perbromate
      Silver iodate
      Silver periodates
      Silver suboxide
      Silver monoxide
      Higher oxides
      Silver subsulphide
      Silver sulphide
      Silver sulphite
      Silver sulphate
      Silver selenide
      Silver telluride
      Silver thiosulphate
      Silver dithionate
      Silver azide
      Silver hyponitrite
      Silver nitrite
      Silver nitrate
      Silver phosphides
      Silver hypophosphate
      Silver orthophosphate
      Silver pyrophosphate
      Silver metaphosphate
      Silver arsenite
      Silver arsenate
      Silver carbide
      Silver carbonate
      Silver cyanide
      Silver thiocyanate
      Silver borate
    PDB 1aoo-3kso

Silver monoxide, Ag2O






Addition of the hydroxide of barium or of an alkali-metal to Silver nitrate solution precipitates the Silver monoxide, Ag2O, as a blackish, amorphous powder, which crystallizes from ammoniacal solution in violet crystals. Its density is given as 7.143 and 7.250. Ammoniacal silver oxide has been known to explode, the phenomenon being probably due to the formation of "fulminating silver".

The monoxide is decomposed by heat into silver and oxygen, the liberated metal playing the part of an autocatalyst in accelerating the reaction. Finely divided platinum and manganese dioxide also cause acceleration of the transformation. It is decomposed by the action of light, with evolution of oxygen, and possibly formation of silver suboxide.

Silver monoxide dissolves in water, forming an alkaline solution which turns red litmus blue. At 25° C. its solubility corresponds with 2.16 × 10-4 gram-molecule per litre of water, and at 15° C. Rebiere found the same value. It is a strong base, its salts having a neutral reaction. The solution is coloured reddish and decomposed by the action of light, the change being possibly attended by deposition of the suboxide or of colloidal silver.

Its heat of formation is about 6.4 Cal. It decomposes hydrogen peroxide, with liberation of metallic silver. With carbon tetrachloride it reacts at 250° C. in accordance with the equation

Ag2O + CCl4 = 2AgCl + COCl2.

In the moist condition it finds extensive application in organic chemistry to the replacement of halogen by hydroxyl. It can act as a reducer.

Argentic oxide, AgO. - A hot alkaline solution of potassium permanganate partially oxidizes silver monoxide to argentic oxide:

Ag2O + 2KMnO4 + 2NaOH = 2AgO + K2MnO4 + Na2MnO4 + H2O.

The reaction is reversible. This oxide is said to be formed by anodic oxidation of silver in alkaline solution. It is a weaker base than the monoxide, but its solution in concentrated nitric acid contains Ag(NO3)2. Barbieri regards it as belonging to the class of ozonides, and differing from the type of oxide exemplified by hydrogen peroxide, because its solution in concentrated nitric acid does not react with lead peroxide, manganese dioxide, or potassium permanganate.


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