What Is Silver Oxide?
Silver oxide is a compound of oxygen and silver. Two types of silver oxide exist: silver oxide (I) and silver monoxide, with silver oxide (I) being commonly referred to as silver oxide. Silver oxide (I) is a dark brown powder obtained by adding a dilute solution of sodium hydroxide to a concentrated solution of silver nitrate.
Silver monoxide, on the other hand, is a grayish-black powder. It forms by the reaction of silver with ozone (O3) and also by the reaction of aqueous silver nitrate with peroxodisulfate, (NH4)2S2O8.
Uses of Silver Oxide
1. Silver Oxide (I)
Silver (I) oxide finds wide application as catalysts, in the sterilization of drinking water, production of colored and conductive glass, glass polishing, hydroxy group introduction in organic synthesis, dehalogenating agent, and medical applications. Its strong bactericidal and deodorizing properties make it suitable for use in cosmetics.
2. Silver Monoxide
Silver monoxide serves various purposes including as oxidants and analytical reagents. It is also utilized in silver oxide-zinc alkaline batteries, which are small primary batteries using zinc as the anode, silver oxide as the cathode, and an alkaline solution as the electrolyte.
Properties of Silver Oxide
Silver oxide (I) is unstable to heat and light, decomposing into silver and oxygen upon exposure to sunlight or heat. It begins decomposing at approximately 160°C and rapidly decomposes at 250-300°C, releasing oxygen to form metallic silver. It completely decomposes at 300-340°C to form solid silver. Silver oxide (I) is insoluble in ethanol.
Silver monoxide is antimagnetic and decomposes into oxygen and silver at temperatures above 100℃. It is one of the strongest oxidizers and is insoluble in cold water but soluble in ammonia water.
Structure of Silver Oxide
1. Silver Oxide (I)
Silver oxide (I) has the chemical formula Ag2O, a formula weight of 231.74, and a density of 7.14 g/cm3. Its crystal structure is cubic, similar to copper (I) oxide, with silver atoms arranged face-centered cubically and oxygen atoms arranged body-centered cubically.
2. Silver Monoxide
Although written with the formula AgO, silver monoxide is not an oxide of silver (II). According to X-ray diffraction results, it is believed to be a mixed oxide of silver (I) and silver (III), such as AgIAgIIIO2.
Other Information on Silver Oxide
1. Reaction of Silver (I) Oxide
Silver oxide (I) is slightly soluble in water, yielding the hydrolysis product Ag(OH2)2–. It reacts with various acids and alkali chloride solutions, forming silver (I) chloride and alkali hydroxides. It also absorbs carbon dioxide in a wet state.
Silver oxide (I) dissolves in aqueous solutions containing ammonia (NH3) and thiosulfate ion (S2O32-), forming complex ions such as silver diamine (I) ion ([Ag(NH3)2]+) and bis-thiosulfato silver (I) acid ion ([Ag(S2O3)2]3-), respectively.
2. Application of Silver (I) Oxide
Silver (I) oxide serves as a mild oxidant in organic chemistry and is used in the synthesis of carboxylic acids from aldehydes. It is often prepared in situ with alkali hydroxides and silver nitrate. Additionally, it is utilized in silver oxide batteries and as a substitute for silver powder in fine electronic circuit manufacturing.