Single-displacement

Displacer units are tolerant of specific gravity shifts within their range, require no power to operate, are intrinsically safe, and can be easily field cahbrated. A single displacer unit can control up to three alarm set points or up to three pumps with different spans. They can be caHbrated for set points or pump spans from 0.15—30 m from the top of the vessel mounting. 

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). 

FIGURE 14.18 Single-displacement bisubstrate mechanism. Double-reciprocal plots of the rates observed with different fixed concentrations of one substrate (B here) are graphed versus a series of concentrations of A. Note that, in these Lineweaver-Burk plots for singledisplacement bisubstrate mechanisms, the lines intersect to the left of the 1/v axis. 

Creatine Kinase Acts by a Random, Single-Displacement Mechanism... 

An example of a random, single-displacement mechanism is seen in the enzyme creatine kinase, a phosphoryl-transfer enzyme that uses ATP as a phosphoryl... 

FIGURE 14.20 Random, single-displacement bisnbstrate mechanism where A does not affect B binding, and vice versa. Note that the lines intersect at the 1/[A] axis. (If [B] were varied in an experiment with several fixed concentrations of A, the lines would intersect at the 1/[B] axis in a 1/u versus 1/[B] plot.)... 

NAD -Dependent Dehydrogenases Show Ordered Single-Displacement Mechanisms... 

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... 

As noted previously, in all cases these various functions describe an inverse sigmoidal curve between the displacing ligand and the signal. Therefore, the mechanism of interaction cannot be determined from a single displacement curve. However, observation of a pattern of such curves obtained at different tracer ligand concentrations (range of [A ] values) may indicate whether the displacements are due to a competitive, noncompetitive, or allosteric mechanism. 

In sequential reactions, both substrates must combine with the enzyme to form a ternary complex before catalysis can proceed (Figure 8-11, top). Sequential reactions are sometimes referred to as single displacement... 

The lack of glycosyl transfer reaction is the class of pectinolytic hydrolases is in agreement with the observed inversion of the anomeric configuration of the newly formed reducing ends of the products. All three polygalacturonases studied here utilize the single displacement mechanism of hydrolysis. 

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. 

In your previous chemistry course, you classified reactions into four main types synthesis, decomposition, single displacement, and double displacement. You also learned to recognize combustion reactions and neutralization reactions. You have now learned to classify redox reactions. In addition, you have also learned about a special type of redox reaction known as a disproportionation reaction. 

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... 

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