To calculate the lattice energy of MgO, we can use the Born-Lande equation:Lattice energy U = N * A * 1 - 1/n * e^2 * |Z+| * |Z-| / 4 * r Where:- N is the Avogadro's number 6.022 x 10^23 mol^-1 - A is the Madelung constant for MgO, A 1.748 - n is the Born exponent for MgO, n 9 - e is the elementary charge 1.602 x 10^-19 C - Z+ and Z- are the charges of the cations and anions, respectively for MgO, Z+ = 2 and Z- = -2 - is the vacuum permittivity 8.854 x 10^-12 C N^-1 m^-2 - r is the distance between the ions 2.1 , which is equivalent to 2.1 x 10^-10 m Now, we can plug in the values and calculate the lattice energy:U = 6.022 x 10^23 * 1.748 * 1 - 1/9 * 1.602 x 10^-19 ^2 * 2 * 2 / 4 * 8.854 x 10^-12 * 2.1 x 10^-10 U 6.022 x 10^23 * 1.748 * 8/9 * 2.566 x 10^-38 * 4 / 1.112 x 10^-10 U 1.052 x 10^-9 / 1.112 x 10^-10 U 9.46 x 10^3 J/molThe lattice energy of MgO is approximately 9,460 J/mol.