Energy diagram for

Fig. VIII-5. Schematic potential energy diagram for electrons in a metal with and without an applied field , work function Ep, depth of the Fermi level. (From Ref. 62.)...

Figure A3.10.17 Potential energy diagram for the dissociative adsorption of N2 [46].

Figure Bl.1.3. State energy diagram for a typical organic molecule. Solid arrows show radiative transitions A absorption, F fluorescence, P phosphorescence. Dotted arrows non-radiative transitions.

The electron-spm echo envelope modulation (ESEEM) phenomenon [37, 38] is of primary interest in pulsed EPR of solids, where anisotropic hyperfme and nuclear quadnipole interactions persist. The effect can be observed as modulations of the echo intensity in two-pulse and three-pulse experiments in which x or J is varied. In liquids the modulations are averaged to zero by rapid molecular tumbling. The physical origin of ESEEM can be understood in tenns of the four-level spin energy diagram for the S = I = model system... 

Figure C2.7.1. Schematic potential energy diagram for tire catalytic syntliesis and decomposition of ammonia on iron. The energies are in kJ mol tire subscript ads refers to species adsorbed on iron [i].

An energy diagram for this reaction is given below (see Figure 3.6). (Note that this is not a representation of the actual reaction path... 

Let us consider the formation of sodium chloride from its elements. An energy (enthalpy) diagram (called a Born-Haber cycle) for the reaction of sodium and chlorine is given in Figure 3.7. (As in the energy diagram for the formation of hydrogen chloride, an upward arrow represents an endothermic process and a downward arrow an exothermic process.)... 

To date there is no evidence that sodium forms any chloride other than NaCl indeed the electronic theory of valency predicts that Na" and CU, with their noble gas configurations, are likely to be the most stable ionic species. However, since some noble gas atoms can lose electrons to form cations (p. 354) we cannot rely fully on this theory. We therefore need to examine the evidence provided by energetic data. Let us consider the formation of a number of possible ionic compounds and first, the formation of sodium dichloride , NaCl2. The energy diagram for the formation of this hypothetical compound follows the pattern of that for NaCl but an additional endothermic step is added for the second ionisation energy of sodium. The lattice energy is calculated on the assumption that the compound is ionic and that Na is comparable in size with Mg ". The data are summarised below (standard enthalpies in kJ) ... 

Let us examine the enthalpy terms involved when an ionic crystal MX is dissolved in water. The energy diagram for a Group I halide is as shown in Figure 3.8. 

FIGURE 3 4 Potential energy diagram for rotation about the carbon-carbon bond in ethane Two of the hydrogens are shown in red and four in green so as to indicate more clearly the bond rotation... 

FIGURE 3 7 Potential energy diagram for rotation around the central carbon-carbon bond in butane... 

A potential energy diagram for nng inversion m cyclohexane is shown m Figure 3 18 In the first step the chair conformation is converted to a skew boat which then proceeds to the inverted chair m the second step The skew boat conformation is an inter mediate in the process of ring inversion Unlike a transition state an intermediate is not a potential energy maximum but is a local minimum on the potential energy profile... 

FIGURE 4 7 Potential energy diagram for proton transfer from hydrogen chio ride to tert butyl alcohol... 

Like tert butyloxonium ion tert butyl cation is an intermediate along the reaction pathway It is however a relatively unstable species and its formation by dissociation of the alkyloxonium ion is endothermic Step 2 is the slowest step m the mechanism and has the highest activation energy Figure 4 8 shows a potential energy diagram for this step... 

Step 3 IS bimolecular because two species the carbocation and chloride ion react together Figure 4 10 shows a potential energy diagram for this step... 

Potential Energy Diagrams for Multistep Reactions The SnI Mechanism... 

POTENTIAL ENERGY DIAGRAMS FOR MULTISTEP REACTIONS THE Sn1 mechanism... 

FIGURE 4 12 Potential energy diagram for the reaction of tert butyl alcohol and hydrogen chloride according to the SnI mechanism... 

Sketch a potential energy diagram for the reaction of 1 heptanol with hydrogen bromide paying careful attention to the positioning and structures of the intermediates and transition states... 

Section 4 9 The potential energy diagrams for separate elementary steps can be merged into a diagram for the overall process The diagram for the reac tion of a secondary or tertiary alcohol with a hydrogen halide is charac terized by two intermediates and three transition states The reaction is classified as a ummolecular nucleophilic substitution, abbreviated as SnI... 

Use Frosts circle to construct orbital energy diagrams for (a) [lOjannulene and (b) [12]annulene Is either aromatic according to Huckel s rule ... 

FIGURE 12 1 Potential energy diagram for elec trophilic aromatic substitu tion... 

FIGURE 12 10 Comparative energy diagrams for nitronium ion attack on (a) benzene and at the (b) ortho (c) meta and (d) para positions of toluene fact (benzene) > fact (meta) > fact (ortho) > fact (para)... 

Approach Temperature—This is defined as the differenee between the saturation temperatures of the steam and the inlet water. Lowering the approaeh temperature ean result in inereased steam produetion, but at inereased eost. Conservatively high-approaeh temperatures ensure that no steam generation takes plaee in the eeonomizer. Typieally, approaeh temperatures are in the 10-20 °F (5.5-11°C) range. Figure 1-40 is the temperature energy diagram for a system and also indieates the approaeh and pineh points in the system. 

Fig. 1.18. Molecular orbital energy diagram for methane. Energies are in atomic units. ...

Fig. 3.3. Potential energy diagram for rotation about C(2)—C(3) bond of n-butane.

Fig. 3.4. Energy diagram for ring inversion of cyclohexane. [For a rigorous analysis of ring inversion in cyclohexane, see H. M. Pickett and H. L. Strauss, J Am. Chem. Soc. 92 7281 (1979).]...

Fig. 3.8. Approximate energy diagram for acetylation of cis- and fronj-4-r-butylcyclohexanol.

Fig. 3.9. Approximate energy diagram for oxidation of cis- and trans-A-t-butylcyclohexanol.

Fig. 3.10. Approximate energy diagram for saponification of ethyl esters of cis- and traKi-4-r-butylcyclohexanecaiboxylic acid.

Reaction coordinate for a two-step reaction Fig. 4.1. Potential energy diagrams for single-step and two-step reactions. 

Fig. 5.5. Potential energy diagrams for substitution mechanisms. A is the S l mechanism. B is the Sjy2 mechanism with intermediate ion-pair or pentacooidi-nate species. C is the classical S).(2 mechanism. [Reproduced from T. W. Bentley and P. v. R. Schleyer, Adv.

Fig. 5.11. Contrasting potential energy diagrams for stable and unstable bridged norbomyl cation. (A) Bridged ion is a transition state for rearrangement between classical structures. (B) Bridged ion is an intermediate in rearrangement of one classical structure to the other. (C) Bridged nonclassical ion is the only stable structure.

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