ФОСФОМОЛИБДАТ АММОНИЯ

Description

Ammonium phosphomolybdate is an anhydrous heteropolysol, tri-ammonium salt of 12-molybdophosphoric acid, CAS 12026-66-3, formula H12Mo12N3O40P. English name Ammonium phosphomolybdate. It belongs to the same class of molybdenum heteropolycompounds as the hydrated form of phosphomolybdate, but has a lower content of water of crystallization.

Basic Attributes

• CAS No.: 12026-66-3
• Chemical formula: H12Mo12N3O40P
• Molecular Weight: 1876.35
• Exact weight: 1899.74000
• EU number: 234-714-0
• HS code: 2842909090
• PSA Specifications: 617.73000
• XLogP3: -2.4883

Physico-chemical characteristics

• Melting point: decomposes
• Boiling point: 100 °C at 760 mmHg. Art.
• Solubility: very slightly soluble in water; soluble in alkali; insoluble in alcohol and acids

Scope of application

Like the hydrate form, it serves as a classic analytical reagent for phosphate ion: it forms a characteristic yellow phosphomolybdate precipitate used in colorimetric methods for determining phosphorus in water, soils, fertilizers, feed and food products. Solubility in alkali and insolubility in alcohol and acids are used as a diagnostic feature in identifying compounds and purifying impurities. Serves as a source of high-purity molybdenum for the production of molybdenum-containing catalysts for hydrotreating, hydrocracking and hydrodesulfurization in oil refining. It is used in the production of special pigments and ceramic coatings, and also as a precipitation reagent for a number of organic bases in analytical and pharmaceutical chemistry.

Thermal behavior

When heated, the salt decomposes without a clear melting point, passing through intermediate oxide phases of molybdenum (including molybdenum trioxide) - this property is used during calcination to obtain molybdenum catalyst masses with a given crystal structure.

Analytical procedure

In the classical method, a sample containing phosphate is treated with a molybdate reagent in an acidic environment; the yellow precipitate that falls is weighed gravimetrically or reduced to molybdenum blue for the spectrophotometric determination of phosphorus.

Precautions

Direct data on the GHS classification and UN transport codes for the anhydrous form are not provided in the source; By analogy with the hydrate form and other molybdates, when working with dry powder, dust formation should be avoided and respiratory and eye protection should be used.

Storage and transportation

Store in a dry, cool place, protected from light, in a tightly closed container - the substance is sensitive to moisture and is capable of slowly absorbing water with the transition to hydrate forms.

Place among heteropoly compounds

The anhydrous form differs from the crystalline hydrate (CAS 54723-94-3) in having a lower water content and, accordingly, a slightly higher relative content of molybdenum in terms of mass - this is taken into account when accurately weighing in analytical and synthetic procedures, where the stoichiometry of molybdenum is important.