![]() Further, its purpose is to bridge the gap between the academic and industrial backgrounds in presenting the established results of research to a wide audience. The present discussion is aimed to attract the attention of researchers from various fields of science to prevent further use of misleading notations and interpretation. ![]() It is thus of great interest to produce scientifically accurate papers that obey the IUPAC (1) notation. The auto-detrimental effect caused by the accumulation of incorrect records is evident in the literature. Another problem may be simply an insufficient level of accuracy, which is not acceptable in scientific records. This is obviously related, not only to the authors of the scientific papers, but also to the reviewers and editors, who are responsible for the correct use of scientific terms. One of the main contributing factors to these mistakes or even misunderstandings may be related to the fact that the corrosion researchers have different backgrounds, not necessarily the most frequent being in chemistry, but in other fields important in corrosion research, such as material science, metallurgy, engineering, and physics. Once published, these incorrect entries persist, being cited and spread further without being recognized as incorrect. This can be seen not only in high-ranking scientific journals concerned with the field, but also in the records of international conferences presented to eminent audiences. Specifically, incorrect notations and even scientific misinterpretations associated with the chemical terms “charge” and “oxidation state” are noted. The pK value for this reaction shows that it are often ignored at pH > 4.More and more incorrect use of chemical nomenclature has appeared in the last decades in the scientific literature concerning the field of corrosion. The dichromate ion may be a somewhat weaker base than the chromate ion. Reported values vary between about −0.8 and 1.6. The hydrogen chromate ion could also be protonated, with the formation of molecular acid, H2CrO4, but the pKa for the equilibrium ![]() It is also in equilibrium with the dichromate ion:Īs a result, this equilibrium doesn’t involve a change in proton concentration, which might predict that the equilibrium is independent of pH. The hydrogen chromate ion, HCrO 4−, maybe a weak acid: Solution All polyoxyanions of chromium(VI) have structures made from tetrahedral CrO4 units sharing corners. Q 1] Explain how condensation reactions occur for chromate and dichromate ions? Oxidation of the chromium to the hexavalent form occurs, while the iron forms iron(III) oxide, Fe2O3.ĤFeCr 2O 4 + 8Na 2CO 3 + 7O 2 → 8Na 2CrO 4 + 2Fe 2O 3 + 8CO 2 Solved Examples for Chromate Formula In addition, chromite ore is heated with a mix of carbonate and washing soda within the presence of air. The primary chromium ore is that the mixed metal oxide chromite, FeCr2O4, found as brittle metallic black crystals or granules. ![]() The redox potential shows that chromates are the weaker oxidant in alkaline solution than in acid solution.ĬrO 2−4 + 4 H 2O + 3 e− → Cr(OH)3 + 5 OH− In alkaline solution chromium(III) hydroxide is produced. In acid solution, there is the production of aquated Cr3+ ion.Ĭr 2O 2−7 + 14 H+ + 6 e− → 2Cr3+ + 7H 2O ε0 = 1.33 V Commonly three electrons are added to a chromium atom, reducing it to oxidation number +3. The chromate and dichromate ions are good strong oxidizing agents. In solution, chromate and dichromate anions exist in equilibrium. But the ion of dichromate can become predominant in acidic solutions. The chromate ion is that the predominant species in alkaline solutions. The position of the equilibrium depends on both pH and therefore the analytical concentration of chromium. In a solution, chromate ions are often interconvertible. Chromate salt of heavy metals, lanthanides, and alkaline-earth metal metals are only very slightly soluble in water and are used as pigments.
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