![]() In the stainless steels, chromium makes up 10 percent or more of the final composition. The addition of chromium imparts hardness, strength, and corrosion resistance to the alloy. The chief use of chromium is to form alloys with iron, nickel, or cobalt. It is an ingredient in several important catalysts. ![]() More than half the production of chromium goes into metallic products, and about another third is used in refractories. The Cr-Cr bond distance in a range of these quadruply bonded species has been found to vary between 195-255 pm. Each Cr(II) ion has 4 d electrons but the complex is found to be diamagnetic which is explained by the formation of a quadruple bond between the two metal ions. 2H 2O is an example of a Cr(II) complex which is reasonably stable in air once isolated. See the laboratory manual for this course for a range of other Cr(III) complexes for which you should know the structure. This allows a small amount of the Cr(II) ion to be formed, which is very labile but unstable with respect to oxidation back to Cr(III). the dark green trans-Cl.2H 2O salt shown above, etc.Īnhydrous CrCl 3 reacts with pyridine only in the presence of Zinc powder.Hydrated chromium chloride, "CrCl 3.6H 2O", exists as hydrate isomers, including: Further deprotonation and polymerization can occur and, as the pH is raised, the final product is hydrated chromium(III) oxide or "chromic hydroxide".Īnhydrous CrCl 3 and hydrated "CrCl 3.6H 2O", The ease with which the proton is removed can be judged by the fact that the hexaaquo ion (pKa ~ 4) is almost as strong as acetic acid. This is thought to occur by the loss of a proton from coordinated water, followed by coordination of the OH - to a second cation: ![]() One of the most obvious characteristics of Cr(III) is that it is acidic i.e it has a tendency to hydrolyse and form polynuclear complexes containing OH - bridges in a process known as OLATION.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |