Lattice energy value

C08-0081. Refer to the lattice energy values in Table Predict the lattice energy of MgS, and explain your prediction. 

The value of the lattice energy is different if other cations and anions form the salt. For example, Na" ions can form salts with anions of any of the halogens. The lattice energy values for each of these salts are about the same. However, when magnesium cations, form salts, these values... 

Molecular dynamics calculations were carried out for Na-Y zeolite with Si/Al ratio of 2.43. Different possible aluminum distributions were considered and their lattice energy values were computed based on simple force-field described in ref 20. It was possible to derive the exact distribution of aluminum, which satisfy the locations of extra framework Na ... 

Crystalline lattice energy values of individual minerals are listed in Table 2.15 and the hydration energy values - in Table 2.16. Hydration energy is proportionate to ion charges. At constant temperature AH are equal to AZ. 

It is clear that improvement of discrimination ratio by molecular anvil goes up as the value of binding energy increases. As for the values of Eo it can be derived from heats of vaporization. Eo is nearly equal to AH 2/z where AH is the value of heat of vaporization and z is the number of nearest neighbours and is between 6 and 12. For heat of vaporization of about 10 K cal. the value of Eo/kT is about 3. For amino acid there is no data of heat of vaporization, but their lattice energy values are of similar order or more, an order of discrimination factor of L-and D-isomer may be explained by this model. 

Lattice energy values for a few common ionic compounds are shown in Figure 3.6 (on the next page). The negative energy values indicate that energy is released when the crystals are formed. 

Order of increasing magnitude of lattice energy KBr < KCl < SrO < CaO Actual lattice energy values ... 

A linear relationship exists between the cohesive energy density of an abrasive (10) and the WoodeU wear resistance values occurring between comndum H = 9) and diamond H = 42.5). The cohesive energy density is a measure of the lattice energy per unit volume. 

Its instability relative to its constituent elements is the result of the high value of / of gold and to its large enthalpy of atomization, which are not compensated for by the small lattice energy. 

These trends are apparent In the values of lattice energy that appear in Table Notice, for example, that the lattice energies of the alkali metal chlorides decrease as the size of the cation increases, and the lattice energies of the sodium halides decrease as the size of the anion increases. Notice also that the lattice energy of MgO is almost four times the lattice energy of LiF. Finally, notice that the lattice energy of Fc2 O3, which contains five ions in its chemical formula, is four times as large as that of FeO, which contains only two ions in its chemical formula. 

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