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A heteropoly acid is a class of acid made up of a combination of hydrogen and oxygen with particular metals and non-metals. The metal addenda atoms linked by oxygen atoms form a cluster with the hetero-atom inside bonded via oxygen atoms. Examples with more than one type of metal addenda atom in the cluster are well known. The conjugate anion of a heteropoly acid is known as a polyoxometalate.

Due to the possibilities of there being different combinations of addenda atoms and different types of hetero atoms there are a lot of heteropolyacids. This type of acid is a common re-usable acid catalyst in chemical reactions. The heteropolyacids are widely used as homogeneous and heterogeneous catalysts, [2] particularly those based on the Keggin structure as they can possess qualities such as good thermal stability, high acidity and high oxidising ability.

Some examples of catalysis are: [3]. Heteropolyacids have long been used in analysis and histology and are a component of many reagents e. From Wikipedia, the free encyclopedia. Chemical Reviews. T Okuhara, M Misono. Encyclopedia of Inorganic Chemistry.

Editor R Bruce King John Wiley and Sons. Categories : Heteropoly acids Acid catalysts. Namespaces Article Talk. Views Read Edit View history. Contribute Help Community portal Recent changes Upload file. By using this site, you agree to the Terms of Use and Privacy Policy. Si , Ge. Mo , W tungsten.


Isopoly and Heteropoly Acids and Salts of Mo and W: Structures of Isopoly and Heteropoly Anions

If these condensed acids contain only one type of acid anhydride, they are called isopoly acids, and their salts are called isopoly salts. The acid anhydrides also can condense with other acids e. The condensation reactions, which occur reversibly in dilute aqueous solution, involve formation of oxo bridges by elimination of water from two molecules of the weak acid. Heteropoly acids and their salts may be formed by coordination of the central atom with four to six oxo anions, which may be mononuclear containing one metal ion each , as in H 7 [P MoO 4 6 ], or trinuclear containing three metal ions each , as in H 3 [P W 3 O 10 4 ]. About 70 elements can act as central hetero atoms in heteropoly anions. Because each element may form more than one heteropoly anion and some of these anions can contain several different heteroatoms, thousands of heteropoly acids exist. Heteroatoms may be primary these atoms are essential to the polyanion structure and thus not susceptible to chemical exchange or secondary these atoms can be removed by chemical reaction from the polyanion structure without destroying it.


Difference Between Isopoly and Heteropoly Acids

The key difference between isopoly and heteropoly acids is that isopoly acids form from the combination of similar acids or anions, whereas heteropoly acids form from the combination of different acids or anions. A poly acid is an acidic compound that forms from the combination of two acids via elimination of a water molecule. If the acids that combine are similar, then the resulting acid is an isopoly acid. But if the final product is a combination of two or more types of acids, then we call it a heteropoly acid. Overview and Key Difference 2. Isopoly acids are inorganic acidic compounds that form from the combination of acids or anions of the same type.


Heteropoly acid




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