What Is Silver Sulfate?
Silver(I) sulfate is a monovalent silver sulfate with the composition Ag2SO4.
The CAS number is 10294-26-5. It is often referred to as silver sulfate (I) sulfate, with the valence number indicated. Silver sulfate is classified as a deleterious substance under the Poisonous and Deleterious Substances Control Law.
Although nonflammable, it can produce irritating or toxic fumes when heated to high temperatures. Theoretically, silver(II) sulfate also exists, but in reality, it is almost nonexistent, and silver sulfate refers to silver(I) sulfate.
Uses of Silver Sulfate
The main uses of silver sulfate are in silver plating materials, synthetic reagents (a source of silver), catalysts, photography, antibacterial materials, hair dyes, and colorants. Silver plating is usually done using silver cyanide, but silver sulfate is attracting attention as a silver plating method that does not use highly toxic cyanide. It is also used in household and medical products, as it is considered the least allergenic of all metals.
1. Wound Dressing and Dye
Due to its antibacterial properties, silver is used in wound dressings and antibacterial products, and is also used in hair coloring agents due to its tendency to turn black under light.
2. Chemical Analysis
A typical use of silver sulfate as a reaction catalyst is in the sulfonation of polystyrene. Silver sulfate is also used in chemical analysis for chemical oxygen demand (COD).
Silver sulfate reacts with chlorine to form silver chloride, so the addition of silver sulfate during COD analysis removes chlorine ions that would otherwise interfere with the measurement. This allows for a catalytic effect that accelerates the reaction.
Properties of Silver Sulfate
Silver sulfate has a molecular weight of 311.799, a melting point of 652°C, a boiling point of 1,085°C (decomposition), and a white or colorless, crystalline or crystalline powder in appearance at room temperature. Its density is 5.45 g/mL. It is soluble in nitric acid, sulfuric acid, and aqueous ammonia, but insoluble in water (solubility in water: 0.796g/100mL).
The crystals are colorless orthorhombic crystals with a face-centered cubic lattice structure.
Types of Silver Sulfate
Silver sulfate is commonly sold as a precious metal chemical product, industrial chemical product, and reagent product for research and development.
1. Precious Metal Chemicals
As a precious metal chemical product, it is sold in units such as 500 g bottles, 5 kg bags, or polyethylene bottles. The main intended applications are reagents, catalysts, colorants, and materials for silver plating.
2. Reagent Products for Research and Development
R&D reagent products are available in 25g, 100g, 500g, and other capacities. In addition to pure substances, they are sometimes sold as sulfuric acid solutions. These reagent products can usually be stored at room temperature.
Other Information on Silver Sulfate
1. Synthesis of Silver Sulfate
Silver sulfate is obtained as a crystalline precipitate by dissolving silver in hot concentrated sulfuric acid and diluting it with water. The byproducts of this reaction are sulfur dioxide and water.
In other methods, crystals are precipitated by adding dilute sulfuric acid or aqueous sulfate solution to an aqueous silver(I) nitrate solution. This method, called aqueous precipitation, is also used in commercial production. Silver(I) sulfide can also be synthesized by calcination of silver(I) sulfide in air at 1085°C or lower.
2. Dissolution of Silver Sulfate
Silver sulfate turns black when decomposed by light. However, it is regarded as a stable substance when stored or handled normally.
In sulfuric acid or nitric acid, silver sulfate forms hydrogen sulfate, and in ammonia water, silver sulfate dissolves by forming an amine complex. The reaction with sulfuric acid is reversible, and silver hydrogen sulfate reverts to silver sulfate through hydrolysis.
3. Regulatory Information on Silver Sulfate
Silver sulfate is designated as a deleterious substance under the Poisonous and Deleterious Substances Control Law. When handling silver sulfate, must be handled properly in compliance with laws and regulations.