Question

Calculate the lattice energy of magnesium oxide (MgO) given that the lattice enthalpy of magnesium (Mg) is 3944 kJ/mol and that of oxygen (O) is 751 kJ/mol.

Answer 1

To calculate the lattice energy of magnesium oxide  MgO , we can use the Born-Haber cycle, which relates the lattice energy to the ionization energy of the metal, the electron affinity of the nonmetal, and the formation enthalpy of the compound.The lattice energy  U  can be calculated using the following equation:U = Hf -  IE + EA Where:- Hf is the enthalpy of formation of MgO- IE is the ionization energy of Mg  3944 kJ/mol - EA is the electron affinity of O  751 kJ/mol First, we need to find the enthalpy of formation  Hf  of MgO. The standard enthalpy of formation of MgO is -601.6 kJ/mol.Now, we can plug the values into the equation:U =  -601.6 kJ/mol  -  3944 kJ/mol + 751 kJ/mol U = -601.6 kJ/mol - 4695 kJ/molU = -5296.6 kJ/molTherefore, the lattice energy of magnesium oxide  MgO  is approximately -5296.6 kJ/mol.