Final answer:
To find the theoretical density of MgO, use the density calculation formula for a cubic unit cell, incorporating the molar mass of MgO, the number of formula units per unit cell (Z), Avogadro's number, and the edge length of the cell.
Step-by-step explanation:
Theoretical Density Calculation for MgO
To calculate the theoretical density of MgO, we need to consider the unit cell geometry, the number of ions, the mass of individual atoms, and the lattice parameter. Magnesium oxide (MgO) crystallizes in a cubic structure. For a simple cubic structure, the density (ρ) can be calculated using the formula ρ = (Z × M) / (N₀ × a³), where Z is the number of formula units per unit cell, M is the molar mass of MgO, N₀ is Avogadro's number, and a is the edge length of the cubic unit cell. In MgO, Z is 1 because one formula unit of MgO fits within the unit cell. The molar mass is the sum of the atomic masses of Mg and O. With the known lattice parameter (a) and the atomic masses, the calculation of the density can be performed. Assuming we know the exact values for a, the atomic masses, and Avogadro's number, we would substitute these into the equation to find the density.
For example, if Mg has an atomic mass of 24.31 g/mol and O has an atomic mass of 16.00 g/mol, the molar mass of MgO would be 40.31 g/mol. If the lattice parameter a is given or calculated based on the ionic radii, and the unit cell has a known volume, we could then find the density using the above formula.