Final answer:
The fraction of atom sites that are vacant for copper at 880K cannot be calculated without the energy of vacancy formation (Qv). Equilibrium vacancy concentration is accessed through the equation Nv = N * exp(-Qv / (k * T)), but Qv is not provided.
Step-by-step explanation:
To calculate the fraction of atom sites that are vacant for copper at 880K, we need to use the concept of vacancy concentration in materials science. This concept applies to the equilibrium number of vacancy sites in a crystal structure at a given temperature. Unfortunately, the information provided doesn't include the energy of vacancy formation for copper or the equation for equilibrium vacancy concentration, which are crucial for this calculation. Therefore, lacking this specific information, it is not possible to provide an accurate answer. Generally, the equation used is:
Nv = N * exp(-Qv / (k * T))
where Nv is the number of vacancies, N is the total number of atomic sites, Qv is the energy required to form one mole of vacancies, k is the Boltzmann's constant, and T is the absolute temperature in Kelvin. Without the vacancy formation energy (Qv), the fraction of vacant atom sites for copper at 880K cannot be calculated from the provided data.