Oxidation number recognizing

An easy way to recognize a redox equation is to note changes in oxidation number of two different elements. The net ionic equation... 

The oxidation number of oxygen in its compounds is -2 except in peroxides (where it is -1), superoxides (where it is - ), or in OF2 and 02F2 (where it is positive). The peroxides and superoxides generally occur only with other elements in their maximum oxidation states. You will be able to recognize peroxides or superoxides by the presence of pairs of oxygen atoms and by the fact that if the compounds were normal oxides, the other element present would have too high an oxidation number (Sec. 13.3). 

In this section, you iearned how to use the oxidation number method to haiance redox equations. You now know various techniques for recognizing and representing redox reactions. In Chapter 11, you will use these techniques to examine specific appiications of redox reactions in the business worid and in your daiiy iife. 

The oxidation number of Fe in K3Fe(CN)6 is +3. To make this assignment, we first recognize cyanide (CN ) as a common ion that carries a charge of —1. Six cyanide ions give —6, and three potassium ions (K+)... 

It is important to recognize that oxidation numbers are a book-keeping device and should not be taken to indicate true charges or even formal charges. In H2Si03—SiO(OH)2—the Si-0 and O-H bonds are... 

Recognizing the empirical nature of oxidation numbers in inorganic chemistry nomenclature, and ending the use of this antiquated concept. 

In Chapter 5, we learned to write formulas for ionic compounds from the charges on the ions and to recognize the ions from the formulas of the compounds. For example, we know that aluminum chloride is AICI3 and that VCI2 contains ions. We cannot make comparable deductions for covalent compounds because they have no ions there are no charges to balance. To make similar predictions for species with covalent bonds, we need to use the concept of oxidation number, also called oxidation state. A system with some arbitrary rules allows us to predict formulas for covalent compounds from the positions of the elements in the periodic table and also to balance equations for complicated oxidation-reduction reactions. 

To write ionic equations, we must recognize compounds that are (1) soluble in water and (2) ionized or dissociated in aqueous solutions. To determine which are oxidation-reduction reactions, we should assign an oxidation number to each element. 

You can always recognize a redox reaction by analyzing oxidation numbers. First determine the oxidation number of each element wherever it appears in the reaction. If no elements change in oxidation numbers, the reaction is not an oxidation-reduction reaction. If changes do occur, the reaction is an oxidation-reduction reaction. Remember that oxidation and reduction must always occur together if some atoms increase in oxidation numbers, then others must decrease. 

The oxidation numbers given in Table 3 can be used to classify organic reactions as either oxidation-reduction reactions or metathesis reactions. Because electrons are neither created nor destroyed, oxidation cannot occur in the absence of reduction, or vice versa. It is often useful, however, to focus attention on one component of the reaction and ask Is that substance oxidized or reduced Assigning oxidation numbers to the individual carbon atoms in a complex molecule can be difficult. Fortunately, there is another way to recognize oxidation-reduction reactions in organic chemistry. 

Compounds with metal-carbon double bonds, which are now known as carbene complexes, were first recognized in 1964 when E. O. Fischer and A. Massbol reported the syntheses of (OC)5M==CR(OR ) (M= Cr, Mo, and W) [13]. This type of carbene complex, which features a low oxidation number of the central metal and heteroatom(s) on the a-carbon, is called a Fischer-type carbene complex and is prepared typically by the following reaction starting from the hexacarbonyls (eq. (1)). 

Corrosion. With the help of oxidation numbers, there are further important redox reactions that can be described, for instance the chemical processes in the corrosion of iron. If one shows in an experiment that iron only goes rusty when water is present in addition to air (see E8.8), then it is possible to recognize the corrosion as a redox reaction ... 

The change in degree of oxidation or reduction can be recognized by a change in oxidation number. 

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