2 results about "Perrhenic acid" patented technology

Perrhenic acid is the chemical compound with the formula Re₂O₇(OH₂)₂. It is obtained by evaporating aqueous solutions of Re₂O₇. Conventionally, perrhenic acid is considered to have the formula HReO₄, and a species of this formula forms when rhenium(VII) oxide sublimes in the presence of water or steam. When a solution of Re₂O₇ is kept for a period of months, it breaks down and crystals of HReO₄·H₂O are formed, which contain tetrahedral ReO⁻₄ For most purposes, perrhenic acid and rhenium(VII) oxide are used interchangeably. Rhenium can be dissolved in nitric or concentrated sulfuric acid to produce perrhenic acid.