![]() ![]() Lattice energies depend on the charge and on the size of the ions in the array. The higher the lattice energy, the stronger the attractions and the higher melting the solid. The lattice energy of an ionic compound is a measure of the attractive forces between the ions. In solid sodium chloride, each positive ion is surrounded by 6 negative ions, and each negative ion is surrounded by 6 positive ions in a cubic lattice array. Most of the energy that is given off is due to the formation of solid sodium chloride from the gaseous ions. The chloride ion reacts with the sodium ion.Ĭl – (g ) + Na + (g ) → NaCl (s) ΔH o rxn = −771 kJĪddition of the five elementary equations gives the sum equation for the formation of solid sodium chloride. This quantity is the electron affinity of chlorine.ĥ. This quantity is the first ionization energy of sodium vapor.Ĭl (g ) + e – → Cl – (g ) ΔH o rxn = −349 kJ Na (g ) → Na + (g ) + e – ΔH o rxn = 496 kJ \frac Cl2 (g ) → Cl (g ) ΔH o rxn = 121 kJ The reaction takes place in five elementary steps: The energy that is released is the enthalpy of formation of solid sodium chloride, which is also called the heat of formation. The reaction between sodium metal and chlorine gas is spontaneous and releases energy. The most reasonable major hydration product of 3,6-dimethylcyclohex-1-ene using water and sulfuric acid is: One workaround for this problem is the oxymercuration-demercuration sequence, as shown here:Ĭonsider the hydration of 3,6-dimethylcyclohex-1-ene under two separate conditions, for which four different alcohol products are proposed: The limitation of this method is that a carbocation is generated along the mechanistic pathway, opening the door to rearrangements, as shown in the sulfuric acid–catalyzed hydration of 3,3-dimethylbut-1-ene here: Many alkenes can be hydrated simply by treatment with a strong acid in the presence of water. MCAT Chemistry Practice Test 2024 Test NameĬhemical and Physical Foundations of Biological Systems ![]()
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