Problem: The standard heat of formation of CaBr2 is -675 kJ/mol. The first ionization energy of Ca is 590 kJ/mol and its second ionization energy is 1145 kJ/mol. The heat of sublimation of Ca is 178 kJ/mol. The bond energy of Br2 is 193 kJ/mol, the heat of vaporization of Br2 (l) is 31 kJ/mol, and the electron affinity of Br is -325 kJ/mol.Calculate the lattice energy of CaBr2.

FREE Expert Solution
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FREE Expert Solution

We’re being asked to calculate the lattice energy of calcium bromide (CaBr2)

Recall that lattice energy is the energy required to combine two gaseous ions into a solid ionic compound:

Mx+(g) + Ny–(g)  MyNx(s)

To calculate for lattice energy, we need to do the Born-Haber cycle for CaBr2

Ca(s) + Br2(g)  CaBr2(s), ΔH˚f

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Problem Details

The standard heat of formation of CaBr2 is -675 kJ/mol. The first ionization energy of Ca is 590 kJ/mol and its second ionization energy is 1145 kJ/mol. The heat of sublimation of Ca is 178 kJ/mol. The bond energy of Br2 is 193 kJ/mol, the heat of vaporization of Br2 (l) is 31 kJ/mol, and the electron affinity of Br is -325 kJ/mol.

Calculate the lattice energy of CaBr2.