Reactivity series metals

Seven chemical reactions were identified from the chemistry syllabus. These chemical reactions were selected because they were frequently encountered during the 2-year chemistiy course and based on their importance in understanding concepts associated with three topics, namely, acids, bases and salts, metal reactivity series and inorganic chemistry qualitative analysis. The seven types of chemical reactions were combustion of reactive metals in air, chemical reactions between dilute acids and reactive metals, neutralisation reactions between strong acids and strong alkalis, neutralisation reactions between dilute acids and metal oxides, chemical reactions between dilute acids and metal carbonates, ionic precipitation reactions and metal ion displacement reactions. Although two of the chemical reactions involved oxidation and reduction, it was decided not to include the concept of redox in this study as students had only recently been introduced to ion-electron... 

Using the metal reactivity series, students are to predict if a chemical reaction would occur when a coil of copper wire is placed in some aqueous silver nitrate in a test-tube. Students are to predict the macroscopic changes that they would expect, given the balanced chemical equation for the above reaction. 

The range of chemical reactivity of metals is wide, from the inertness of the platinum group to the extreme reactivity of some alkali metals. The order of metal reactivity follows essentially the order of the electrochemical series which is shown in Table 17.4 for the metals commonly deposited by CVD. 

A comparison of this equation with the equations provided above points out that lead (IV) oxide is clearly not a base. The nature of metallic hydroxides varies according to the position of the metal in the reactivity series, as given in Table 6.3. Metallic hydroxides are electrovalent compounds, composed of metal ions, which are positively charged, and hydroxy ions, OTT. The number of OTT ions associated with one metallic ion is equal to the valency of the metal, e.g., Na+OH sodium is monovalent Ca2+(OTT)2 calcium is divalent. The metallic hydroxides form a very important series of compounds, and are known to have many uses both in the laboratory and in industry. 

Hering, J. G. and Morel, F. M. M. (1990). The kinetics of trace metal complexation implications for metal reactivity in natural waters. In Aquatic Chemical Kinetics -Reaction Rates of Processes in Natural Waters, ed. Stumm, W., Wiley Interscience Series on Environmental Science and Technology, New York, pp. 145-171. 

You already know that some metals are more reactive than others. You may also have carried out an investigation on the metal activity series in a previous course. In Investigation 10-A, located on page 470, you will discover how this series is related to oxidation and reduction. You will write chemical equations, ionic equations, and half-reactions for the single displacement reactions of several metals. 

The metal activity series is shown in the table helow. The more reactive metals are near the top of the series, and the less reactive metals are near the bottom. In this investigation, you will relate the activity series to the ease with which metals are oxidized and metal ions are reduced. 

This particular nucleophilic reactivity series which we find for silicon(IV) is not necessaiily characteristic of what one would expect to find for all different metal ions. And in fact, we know in the case of platinum (I I), where Sn2 reactions seem to occur quite commonly, that we get quite a different nucleophilic reactivity series. The variation in rates for platinum (I I) is almost as large as this. I don t know that an actual range of 109 has been covered yet, but the order of the different nucleophiles is quite different. 

Describe how simple chemical cells can be used to confirm the order of reactivity of the metals in the reactivity series. 

If similar reactions are carried out using other metals with acid, an order of reactivity can be produced by measuring the rate of evolution of hydrogen. This is known as a reactivity series. 

Give a use for each of the other unreactive metals shown in the reactivity series. 

The ways in which metal nitrates, carbonates, oxides and hydroxides decompose can also be discussed in terms of the reactivity series of the metals. The decomposition processes are different, depending on the position of the metal in the reactivity series. 

Generally, it is the unreactive metals for which we find most uses. For example, the metals iron and copper can be found in everyday objects such as car bodies and coins, respectively However, the metal aluminium is an exception. Aluminium appears in the reactivity series just below magnesium and is quite reactive. 

The reactivity series is useful for predicting how metals will react. It can also be used to predict the reactions of some metal compounds. The tables on... 

A more reactive metal has a greater tendency to form a metal ion by losing electrons than a less reactive metal does. Therefore, if a more reactive metal is heated with the oxide of a less reactive metal, then it will remove the oxygen from it (as the oxide anion). You can see from the reactivity series that iron is less reactive than aluminium (p. 150). If iron(m) oxide is mixed with aluminium and the mixture is heated using a magnesium fuse (Figure 10.6), a very violent reaction occurs as the competition between the aluminium and the iron for the oxygen takes place. 

In another reaction, metals compete with each other for other anions. This type of reaction is known as a displacement reaction. As in the previous type of competitive reaction, the reactivity series can be used to predict which of the metals will win . 

In a displacement reaction, a more reactive metal will displace a less reactive metal from a solution of its salt. Zinc is above copper in the reactivity series. 

How could you carry out a series of reactions between metals and solutions of their nitrates to establish a reactivity series ... 

This is also a redox reaction involving the transfer of two electrons from the zinc metal to the copper ions. The zinc is oxidised to zinc ions in aqueous solution, while the copper ions are reduced. (See Chapter 5, p. 73, for a discussion of oxidation and reduction in terms of electron transfer.) It is possible to confirm the reactivity series for metals using competition reactions of the types discussed in this section. 

Over the centuries other metals, which like iron are also relatively low in the reactivity series, were isolated in a similar manner. These included copper, lead, tin and zinc. However, due to the relatively low abundance of the ores containing these metals, they were not extracted and used in large amounts. 

Metals high in the reactivity series have proved very difficult to isolate. It was not until more recent times, through Sir Humphry Davy s work on electrolysis, that potassium (1807), sodium (1807), calcium (1808) and magnesium (1808) were isolated. Aluminium, the most plentiful reactive metal in the Earth s crust, was not extracted from its ore until 1827, by Friedrich Wohler (p. 74), and the extremely reactive metal rubidium was not isolated until 1861 by Robert Bunsen and Gustav Kirchhoff. 

Targe lumps of the ore are first crushed and ground up by very heavy machinery. Some ores are already fairly concentrated when mined. For example, in some parts of the world, haematite contains over 80% Fe2Os. However, other ores, such as copper pyrites, are often found to be less concentrated, with only 1% or less of the copper compound, and so they have to be concentrated before the metal can be extracted. The method used to extract the metal from its ore depends on the position of the metal in the reactivity series. 

Metals towards the middle of the reactivity series, such as iron and zinc, may be extracted by reducing the metal oxide with the non-metal carbon. 

How does the method used for extracting a metal from its ore depend on the metal s position in the reactivity series ... 

Metal extraction The method used to extract a metal from its ore depends on the position of the metal in the reactivity series. 

Moderately reactive metals (those near the middle of the reactivity series) are extracted using a chemical reducing agent (for example carbon) in a furnace for example, iron from haematite in the blast furnace. 

Reactivity series of metals An order of reactivity, giving the most reactive metal first, based on results from experiments with oxygen, water and dilute hydrochloric acid. 

Copper is less reactive than either zinc or magnesium. A more reactive metal will always displace a less reactive metal from its salt solution but the opposite reaction is not possible. Reactivity of metals can be arranged in an order (Reactivity series). 

O transition metal a metal in the central block of the Periodic Table transition metals are hard, dense metals that form coloured compounds and can have more than one valency O reactivity series a listing of the metals in order of their reactivity 0 O electrochemical cell a cell made up of two metal electrodes of different reactivity placed it an... 

Using the results of various different types of chemical reaction the metals can be arranged into the reactivity series. 

C Choose one metal from the reactivity series that will safely react with dilute sulfuric acid. 

In the same way, any metal below carbon in the reactivity series can be extracted from its ore by heating the ore with carbon, because the carbon will displace the metal. The most important of these reactions, because our civilisation depends so much on steel, which is an alloy of iron, is the production of iron by heating iron ore (iron oxide) with coke (which is a form of carbon). The carbon, being more reactive than iron, displaces it thus ... 

On the other hand, if you heat sodium oxide, nothing happens. This is because sodium is towards the very top of the reactivity series. It was eager to form positive ions in the first place by giving away electrons, so sodium ions are less likely than mercury ions to accept the electrons back again and form neutral atoms. The general rule is that the more reactive a metal is, the more stable its compounds are likely to be, i.e. the less likely to be split up by heating. 

Sodium can only be extracted by electrolysing molten salt (sodium chloride). See Section 3.2.2 for the explanation of electrolysis. The top four metals in the reactivity series shown here were not discovered until electrolysis of their molten compounds became possible early in the nineteenth century (see Section 3.2.1). 

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