Activity series, common metals

Single replacement reactions in which metals replace other metals cire especially common. Not all single replacement reactions occur as written, though. You sometimes need to refer to a chart called the activity series to determine whether such a reaction will take place. 

Tables containing the same sequence of reactions as in Table 1, but without the voltage data, were in common use long before electrochemical cells were studied and half-cell potentials had been measured. If you read down the central column, you will notice that it begins with the sequence of metals Na, Zn, Fe, etc. This sequence is known as the activity series of the metals, and expresses the decreasing tendency these species to lose electrons- that is, to undergo oxidation.

Processes which involve oxidation (the loss of electrons or the gain of relative positive charge) and reduction (the gain of electrons or the loss of relative positive charge) are typical of these reactions. Use of Table 8.1, the activity series of common metals, enables chemists to predict which oxidation-reduction reactions are possible. A more active metal, one higher in the table, is able to displace a less active metal, one listed lower in the table, from its aqueous salt. Thus aluminum metal displaces copper metal from an aqueous... 

You can use Figure 10-10 to predict whether or not certain reactions will occur. A specific metal can replace any metal listed below it that is in a compound. It caimot replace any metal listed above it. For example, you saw in Figure 10-9 that copper atoms replace silver atoms in a solution of silver nitrate. However, if you place a silver wire in aqueous copper(II) nitrate, the silver atoms will not replace the copper. Silver is listed below copper in the activity series and no reaction occurs. The letters NR (no reaction) are commonly used to indicate that a reaction will not occur. 

Table 4-12 lists the activity series. When any metal listed above hydrogen in this series is added to a solution of a nonoxidizing acid such as hydrochloric acid, HCl, and sulfuric acid, H2SO4, the metal dissolves to produce hydrogen, and a salt is formed. HNO3 is the common oxidizing acid. It reacts with active metals to produce oxides of nitrogen, but not... 

Nonoxidizing acids react with metals above hydrogen in the activity series (Section 4-8, part 2) to liberate hydrogen gas, H2. (HNO3, a common oxidizing acid, reacts with metals to produce nitrogen oxides, not H2.)... 

The alloy catalysts used in these early studies were low surface area materials, commonly metal powders or films. The surface areas, for example, were two orders of magnitude lower than that of platinum in a commercial reforming catalyst. Hence these alloys were not of interest as practical catalysts. The systems emphasized in these studies were combinations of metallic elements that formed continuous series of solid solutions, such as nickel-copper and palladium-gold. The use of such systems presumably made it possible to vary the electronic structure of a metal crystal in a known and convenient manner, and thereby to determine its influence on catalytic activity. Bimetallic combinations of elements exhibiting limited miscibility in the bulk were not of interest. Aspects of bimetallic catalysts other than questions related to the influence of bulk electronic structure received little attention in these studies. 

Nitric acid is a powerful oxidizing agent. The oxidation number of N in HNO3 is -1-5. The most common reduction products of nitric acid are NO2 (oxidation number of N = -1-4), NO (oxidation number of N = -1-2), and NH4 (oxidation number of N = -3). Nitric acid can oxidize metals both below and above hydrogen in the activity series (see Figure 4.15). For example, copper is oxidized by concentrated nitric acid, as discussed earlier. 

Many common redox reactions involve elements as reactants or products. In an activity series, metals are ranked according to their ability to displace H2 (reduce H ) from water or acid or reduce the cation of another metal from solution. 

The notation (aq) indicates that the compound is dissolved in water — in an a<7ueous solution. Because zinc replaces copper in this case, it s said to be more active. If you place a piece of copper in a zinc sulfate solution, nothing will happen. Table 8-1 shows the activity series of some common metals. Notice that because zinc is more active in the table, it will replace copper, just as the preceding equation shows. 

A common chemical reaction is the displacement of hydrogen from water or acids (shown in 1 and 2 above). This reaction is a good illustration of the relative reactivity of metals and the use of the activity series. For example,... 

A list of metals arranged in order of decreasing ease of oxidation is called an activity series. Table 4.5 T gives the activity series in aqueous solution for many of tile most common metals. Hydrogen is also included in the table. The metals at tile top of tile table, such as tiie alkali metals and the alkaline earth metals, are most easily oxidized that is, tiiey react most readily to form compoxmds. They... 

The standard electrode potentials for some common metals are given in Table 19.1. Note that the half-cell reactions are written as reduction processes the metal ions are gaining electrons. The standard electrode potentials are therefore sometimes known as standard reduction potentials. This arrangement of metals (and hydrogen) in order of decreasing standard electrode potential is known as the electrochemical series. It is very similar in arrangement to the activity series (Chapter 9). 

Table 7-1 shows the activity series of some common metals. Notice that because zinc is more active in the table, it will replace copper, just as the earlier equation shows. 

If dissimilar metals are placed in contact, in an electrolyte, the corrosion rate of the anodic metal will be increased, as the metal lower in the electrochemical series will readily act as a cathode. The galvanic series in sea water for some of the more commonly used metals is shown in Table 7.4. Some metals under certain conditions form a natural protective film for example, stainless steel in oxidising environments. This state is denoted by passive in the series shown in Table 7.4 active indicates the absence of the protective film. Minor... 

Nucleophilic substitution reactions, to which the aromatic rings are activated by the presence of the carbonyl groups, are commonly used in the elaboration of the anthraquinone nucleus, particularly for the introduction of hydroxy and amino groups. Commonly these substitution reactions are catalysed by either boric acid or by transition metal ions. As an example, amino and hydroxy groups may be introduced into the anthraquinone system by nucleophilic displacement of sulfonic acid groups. Another example of an industrially useful nucleophilic substitution is the reaction of l-amino-4-bromoanthraquinone-2-sulfonic acid (bromamine acid) (76) with aromatic amines, as shown in Scheme 4.5, to give a series of useful water-soluble blue dyes. The displacement of bromine in these reactions is catalysed markedly by the presence of copper(n) ions. 

Despite of the common reaction mechanism, peroxo complexes exhibit very different reactivities - as shown by the calculated activation energies -depending on the particular structure (nature of the metal center, peroxo or hydroperoxo functionalities, type and number of ligands). We proposed a model [72, 80] that is able to qualitatively rationalize differences in the epoxidation activities of a series of structurally similar TM peroxo compounds CH3Re(02)20-L with various Lewis base ligands L. In this model the calculated activation barriers of direct oxygen transfer from a peroxo group... 

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