Perrhenic acid

• Hydrogenperrhenat
• Hydrogentetraoxorhenat

Colorless to pale yellow liquid

Liquid (solution)

• 2.16 g · cm -3 ( 25 ° C)
• 4.87 g · cm -3

23 hPa (20 ° C)

Miscible with water

Risk

Template: Infobox chemical / molecular formula search available

Perrhenic acid is an inorganic chemical compound consisting of the group of acids. It is available only in aqueous solution. As solid perrhenic Dirheniumdihydratoheptoxid Re.sub.2O.sub.7 ( OH2 ) 2 is called.

Production and representation

An aqueous perrhenic acid solution can be obtained by reaction of hydrogen peroxide with rhenium.

Also possible is the representation by dissolution of rhenium (VII ) oxide in water.

The solutions can only be added to a concentration of max. Be evaporated 70 weight percent HReO4, over it HReO4 volatilized.

Fixed perrhenic can be obtained from an aqueous solution as concentrated as possible perrhenic by being freed from the excess of water in a desiccator by means of phosphorus pentoxide or magnesium perchlorate.

Properties

Perrhenic is a pure substance can not be displayed and only exist as colorless to pale yellow solution. Dirheniumdihydratoheptoxid is a pale yellow, very hygroscopic solid. It is soluble in nitromethane and decomposes at 65 ° C volatilization of HReO4. It has a monoclinic crystal structure with space group P21 / m ( a = 882 pm, b = 889 pm, c = 503 pm, P = 112.0 ° ) with O3Re -O- ReO3 ( OH2 ) 2 molecules.

Use

Perrhenic used to represent well-conducting and superconducting synthetic metals.