Single-displacement reactions

In single displacement reactions, a more active element displaces (kicks out) another less active element from a compound. For example, if you put a piece of zinc metal into a copperGO sulfate solution (by the way. Chapter 6 explains why copperGO sulfate is named the way it is — in case you re wondering), the zinc displaces the copper, as shown in this equation  

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. 

Take another look at the reaction between zinc metal and copperOD) sulfate solution  

Equatiorrs written in this form, in which the ions are shown separately, are called ionic equations (because they show the reaction and production of ions). Notice that the sulfate ion, 804 , hasn t changed in the reaction. Ions that don t change during the reaction and are found on both sides of the equation in an identical form are called spectator ions. Chemists (a lazy, lazy lot, they are) often omit the spectator ions and write the equation showing only those chemical substances that are changed during the reaction. This is called the net-ionic equation  

In single displacement reactions, only one chemical species is displaced. In double displacement reactions, or metathesis reactions, two species (normally ions) are displaced. Most of the time, reactions of this t3 e occur in a solution, and either an insoluble solid (precipitation reactions) or water (neutralization reactions) will be formed. 

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Reactions of this type are defined as sequential or single-displacement reactions. They can be either of two distinct classes ... 

Both classes of single-displacement reactions are characterized by lines that intersect to the left of the 1/v axis in Lineweaver-Burk doublereciprocal plots (Figure 14.18). 

Maltose phosphorylase proceeds via a single-displacement reaction that necessarily requires the formation of a ternary maltose E Pi (or glucose E glucose-l-phosphate) complex for any reaction to occur. Exchange reactions are a characteristic of enzymes that obey double-displacement mechanisms at some point in their catalysis. 

The general rate equation for an ordered, single-displacement reaction where A is the leading substrate is... 

The electrons that are being lost by the zinc metal are the same electrons that are being gained by the copper(II) ion. The zinc metal is being oxidized and the copper(II) ion is being reduced. Further discussions on why reactions such as these occur can be found in the section on single-displacement reactions later in this chapter. 

Single displacement (replacement) reactions are reactions in which atoms of an element replace the atoms of another element in a compound. All of these single replacement reactions are redox reactions, since the element (in a zero oxidation state) becomes an ion. Most single displacement reactions can be categorized into one of three types of reaction ... 

Single displacement reactions are redox reactions in which atoms of an element replace the atoms of another element in a compound. 

Sigma (a) bonds Sigma bonds have the orbital overlap on a line drawn between the two nuclei, simple cubic unit cell The simple cubic unit cell has particles located at the corners of a simple cube, single displacement (replacement) reactions Single displacement reactions are reactions in which atoms of an element replace the atoms of another element in a compound, solid A solid is a state of matter that has both a definite shape and a definite volume, solubility product constant (/ p) The solubility product constant is the equilibrium constant associated with sparingly soluble salts and is the product of the ionic concentrations, each one raised to the power of the coefficient in the balanced chemical equation, solute The solute is the component of the solution that is there in smallest amount, solution A solution is defined as a homogeneous mixture composed of solvent and one or more solutes. 

In your previous chemistry course, you compared the reactivities of metals. You may recall that, when a piece of zinc is placed in an aqueous solution of copper(II) sulfate, the zinc displaces the copper in a single displacement reaction. This reaction is shown in Figure 10.1. As the zinc dissolves, the zinc strip gets smaller. A dark red-brown layer of solid copper forms on the zinc strip, and some copper is deposited on the bottom of the beaker. The blue colour of the solution fades, as blue copper(ll) ions are replaced by colourless zinc ions. 

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. 

For each single displacement reaction you observed, write... 

Predict whether each of the following single displacement reactions will occur. If so, write a balanced chemical equation, a balanced net ionic equation, and two balanced half-reactions. Include the physical states of the reactants and products in each case. 

O The element potassium is made industrially by the single displacement reaction of molten sodium with molten potassium chloride. 

You have seen that the single displacement reaction of zinc with copper(II) sulfate is a redox reaction, represented by the following chemical equation and net ionic equation. 

Magnesium exhibits single displacement reactions, thus replacing lower metals in electrochemical series from their salt solutions or melt. For example, magnesium will replace iron from molten iron(II) chloride forming magnesium chloride ... 

Single displacement reaction where magnesium is displacing hydrogen in the water molecule. 

In a single replacement reaction (sometimes referred to as a single displacement reaction), a single, more reactive element or group replaces a less reactive element or group, following the general pattern... 

Figure 2. Geoffroys 1718 affinity table for single displacement reactions interpreted as particle interchanges.

Alternatives to the oxocarbenium ion mechanism are the direct attack of water on the substrate, and the nucleophilic attack of Asp-52 on the C-1 carbon to give an ester intermediate. The single-displacement reaction has been ruled out by showing that the reaction proceeds with retention of configuration (Chapter 7, section C3 Chapter 8, section C2).212-214 The oxocarbenium ion or SN1 mechanism has been substantiated by secondary isotope effects, using substrates containing either deuterium or tritium instead of hydrogen attached to the C-1 carbon 215 216 For example, kK/kD for structures 16.42 is 1.11,... 

A large number of possible enzyme-substrate complexes may form, e.g. the binary complexes EA, EB, EP and EQ, ternary complexes EAB, EPQ, EAQ, and EBQ. Most two-substrate reactions can be grouped into two major classes, based upon the reaction sequence in the two-substrate reactions, single displacement reactions and double displacement reactions. 

In single displacement reactions both substrates A and B simultaneously must be present on the active site of the enzyme to yield a ternary complex EAB in order that the reaction may proceed. Single displacement reactions take place in two forms, random and ordered, and they are distinguished by the way the two substrates bind to the enzyme. 

In a single displacement reaction, one element switches places with another element in a compound. The reactants in a single displacement reaction are an element and a compound, and the products are a different element and a different compound. A single displacement reaction can also be called a single replacement reaction. Look at this example of a single displacement reaction ... 

Many metals, such as zinc, iron, lead, copper, and aluminum are found chemically bonded to oxygen in nature. Sometimes, chemists can use single displacement reactions to get the pure metal. 

Not all reactions are redox reactions. Only the ones in which electrons are transferred from one reactant to another are classified as redox reactions. Many single-displacement reactions, combination reactions, decomposition reactions, and combustion reactions are redox reactions. Double displacement reactions never involve the transfer of electrons and are not, therefore, redox reactions. Since acid-base reactions are just a special type of double displacement reaction, they cannot be redox reactions, either. 

Single displacement reaction A chemical reaction in which an element replaces one ion in a compound. It has the general formula A + By - Ay + B. 

Single replacement reaction See single displacement reaction. 

In a single displacement reaction, one element in a compound is displaced (or replaced) by another element. Two general reactions represent two different types of single displacement reactions. One type involves a metal replacing a metal cation in a compound, as follows ... 

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