![]() ![]() The lattice energy is negative and the hydration energy is positive. The lattice energy is positive and the hydration energy is negative. For KCl, the absolute value of the hydration energy is smaller than the absolute value of its lattice energy For KCl, the absolute value of the hydration energy is larger than the absolute value of its lattice energy Whether the dissolving of a salt is endothermic or exothermic depends on the balance between the lattice energy (can be defined as the energy required to pull the ions of the salt apart from one another) and the hydration energy (the energy associated with the process when the water molecules surround the ions in solution).īased, on the information above, which of the following statements are true? The larger negative value we have for the lattice energy, the more energy released when the lattice was formed, and thus the stronger the lattice structure and the higher the bond order.When CaCl2 is dissolved in water the temperature of the resulting solution increases, but when KCl is dissolved in water the resulting solution has a temperature that is lower than that of the starting water. #color(blue)(DeltaH_"lattice"("CsI") = -"604 kJ/mol")# In one definition, the lattice energy is the energy required to break apart an ionic solid and convert its component atoms into gaseous ions. #DeltaH_"lattice"("SrS") = ?# (cannot find) The Born-Haber cycle can be used to determine the lattice energy of an ionic compound that might not be possible to create in the laboratory. Heat is released when an ionic compound is formed making the reaction exothermic. ![]() #"CsI"# ( smallest charge magnitude less similar ionic radii than #"KBr"# larger ionic radii than #"KBr"# as a #pm1# ionic compound) The lattice energy is the energy involved in the formation of an ionic compound from its gaseous ions.#"KBr"# ( smallest charge magnitude most similar ionic radii smallest ionic radii as a #pm1# ionic compound).#"SrS"# ( highest charge magnitude large difference in ionic radii).So, we expect the highest lattice energy to least lattice energy to be: The above three methods of comparison are all ordered by their effect on decreasing bond strength. The charge magnitude affects the lattice energy the most by far, followed by the actual ionic radii. #"184 pm"#, #Deltar_("ionic") = "52 pm"#)Īnd finally, in order of largest to smallest charge magnitude, we have: ![]() In order of most similar to least similar ionic radii, we have: In order of smallest to largest ionic radii, we have: Now consider these ions on the periodic table: Increasing bond order is directly proportional to increasing lattice energy. The larger the charge magnitudes of the cation and anion, the stronger the bond.The smaller the difference in ionic radii between the cation and anion, the stronger the bond.The smaller the ionic radii of the cation and anion, the stronger the bond.When considering ionic compounds, we expect the following typical trends: Well, they're all ionic compounds, so the only practical way to obtain the "bond order" is through the lattice energies.īond order, qualitatively speaking, is proportional to the bond strength.
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