Iso Poly Acids and Heteropoly Acids: A Review of Their Synthesis, Characterization, and Functionality
- Why are they important in chemistry? - What are some examples of iso poly acids and heteropoly acids? H2: Isopoly acids and salts of chromium - How are they formed from chromate ions? - What are their structures and properties? - What are some applications of isopoly chromates? H2: Isopoly acids and salts of molybdenum and tungsten - How are they formed from molybdate and tungstate ions? - What are their structures and properties? - What are some applications of isopoly molybdates and tungstates? H2: Heteropoly acids and salts - How are they formed from isopoly acids and other acids? - What are their structures and properties? - What are some applications of heteropoly acids and salts? H1: Conclusion - Summarize the main points of the article - Provide some future directions for research on iso poly acids and heteropoly acids H2: FAQs - Answer five common questions about iso poly acids and heteropoly acids # Article with HTML formatting Introduction
If you are interested in learning about some fascinating compounds in inorganic chemistry, you might want to read this article on iso poly acids and heteropoly acids. These are complex anions that contain multiple metal atoms bonded to oxygen atoms, forming various shapes and structures. They have diverse properties and applications in catalysis, electrochemistry, medicine, and more.
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But what exactly are iso poly acids and heteropoly acids? How are they different from each other? And what are some examples of these compounds? Let's find out!
Isopoly acids and salts of chromium
One of the simplest examples of iso poly acids and salts is the chromate ion, CrO4. This is a tetrahedral anion that forms when chromium trioxide, CrO3, dissolves in an alkali solution. The chromate ion has a bright yellow color and can be isolated as sodium or potassium chromate, Na2CrO4 or K2CrO4.
However, when the pH of the solution is lowered, the chromate ion undergoes protonation and polymerization, forming larger anions with more chromium atoms. These are called isopoly chromates, because they contain only one type of metal (chromium) along with hydrogen and oxygen. For example, two chromate ions can combine to form a dichromate ion, Cr2O7, which has a red-orange color. Similarly, three chromate ions can form a trichromate ion, Cr3O10, which has a green color. And four chromate ions can form a tetrachromate ion, Cr4O13, which has a blue color.
The isopoly chromates have different structures than the chromate ion. They consist of tetrahedral units joined by shared oxygen atoms, forming chains or rings. The Cr-O-Cr bond angle in all isopoly chromates is approximately 120 degrees. The isopoly chromates can also be isolated as sodium or potassium salts, such as K2Cr2O7, K2Cr3O10, or K2Cr4O13.
The isopoly chromates have various applications in chemistry and industry. For example, they can be used as oxidizing agents, as indicators in titrations, as dyes and pigments, and as corrosion inhibitors.
Isopoly acids and salts of molybdenum and tungsten
Another example of iso poly acids and salts is the molybdate ion, MoO4. This is also a tetrahedral anion that forms when molybdenum trioxide, MoO3, dissolves in an alkali solution. The molybdate ion has a white color and can be isolated as sodium or potassium molybdate, Na2MoO4 or K2MoO4.
Like the chromate ion, the molybdate ion can also undergo protonation and polymerization, forming larger anions with more molybdenum atoms. These are called isopoly molybdates, because they contain only one type of metal (molybdenum) along with hydrogen and oxygen. For example, six molybdate ions can combine to form a paramolybdate ion, Mo6O19, which has a yellow color. Similarly, twelve molybdate ions can form a heptamolybdate ion, Mo7O24, which has a green color. And eighteen molybdate ions can form a decamolybdate ion, Mo10O32, which has a blue color.
The isopoly molybdates have different structures than the molybdate ion. They consist of octahedral units joined by shared edges or vertices, forming clusters or cages. The Mo-O-Mo bond angle in all isopoly molybdates is approximately 90 degrees. The isopoly molybdates can also be isolated as sodium or potassium salts, such as Na2Mo6O19, K6Mo7O24, or K4Mo10O32.
The isopoly molybdates have various applications in chemistry and industry. For example, they can be used as catalysts, as electrodes in batteries, as sensors and detectors, and as anticancer agents.
The same process of protonation and polymerization can also occur with the tungstate ion, WO4, which forms when tungsten trioxide, WO3, dissolves in an alkali solution. The tungstate ion has a white color and can be isolated as sodium or potassium tungstate, Na2WO4 or K2WO4. The tungstate ion can also form larger anions with more tungsten atoms, called isopoly tungstates. These have similar structures and properties to the isopoly molybdates, but with different colors. For example, the paramolybdate ion has a yellow color, while the paratungstate ion has a red color.
Heteropoly acids and salts
Besides forming iso poly acids and salts, the metal oxides of chromium, molybdenum, and tungsten can also form heteropoly acids and salts. These are complex anions that contain two or more different types of metals (or nonmetals) along with hydrogen and oxygen. For example, the metal oxides can react with phosphoric acid or silicic acid to form heteropoly acids and salts.
The heteropoly acids and salts have different structures and properties than the iso poly acids and salts. They consist of octahedral units joined by shared edges or vertices, forming clusters or cages. However, some of the octahedral units are replaced by tetrahedral units of phosphorus or silicon atoms. The heteropoly acids and salts have various colors depending on the type and number of atoms involved.
The heteropoly acids and salts have various applications in chemistry and industry. For example, they can be used as catalysts, as electrodes in fuel cells, as antiviral agents, and as optical materials.
Conclusion
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