Problem: Use the data given below to construct a Born-Haber cycle to determine the heat of formation of KCl.H °(kJ)K(g) → K+(g) + e-418Cl2(g) → 2 Cl(g)244Cl(g) + e- → Cl-(g)-349KCl(s) → K+(g) + Cl-(g)717

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FREE Expert Solution

We’re being asked to calculate the enthalpy of formation of KCl, given the lattice energy. 


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 KCl. We start with the corresponding formation equation for KCl:

K(s) + ½ Cl2(g)  KCl(s), ΔH˚f


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Problem Details

Use the data given below to construct a Born-Haber cycle to determine the heat of formation of KCl.


\DeltaH °(kJ)
K(g) → K+(g) + e-418
Cl2(g) → 2 Cl(g)244
Cl(g) + e- → Cl-(g)-349
KCl(s) → K+(g) + Cl-(g)717

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