Concept explainers
Calculate the lattice energy of calcium chloride given that the heat of sublimation of Ca is 121 kJ/mol and ΔH°f(CaCl2 ) = −795 kJ/mol. (See Tables 8.2 and 8.3 for other data.)
Interpretation:
Lattice energy of Calcium chloride has to be calculated using given data.
Concept Introduction:
Born-Haber cycle is based on Hess’s law to calculate the lattice enthalpy of ionic compounds and deals with energy changes in formation of ionic compounds.
The energy released when gaseous state ions of unlike charges that are infinitely farther apart combine to form a stable ionic solid is called Lattice energy. Conversely, the energy required to break the electrostatic force of attraction between the ions of unlike charges in the ionic solid and revert them to gaseous state is also termed as Lattice energy of an ionic solid.
Hess’s law is applied to calculate the enthalpy changes in a reaction. According to Hess’s law – “The overall enthalpy change of a reaction is equal to the sum of the enthalpy changes involving in each and every individual steps in the reaction”. Thus if a reaction involves ‘n’ steps then enthalpy change
Answer to Problem 9.26QP
Lattice energy of Calcium chloride
Explanation of Solution
Given data:
The first step of Born-Haber cycle involves sublimation of solid
The second step of Born-Haber cycle involves dissociation of gaseous
The third step of Born-Haber cycle is ionization of gaseous
The fourth step of Born-Haber cycle is ionization of gaseous
The fifth and final step of Born-Haber cycle is formation of solid
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Chapter 9 Solutions
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