To calculate the average atomic mass of copper (Cu), you need to consider the relative abundances and masses of its isotopes, Cu-63 and Cu-65.
Given that the sample of copper contains 69.17% Cu-63, the remaining percentage will be Cu-65. Therefore, the abundance of Cu-65 can be calculated as:
Abundance of Cu-65 = 100% - 69.17% = 30.83%
The atomic mass of Cu-63 is approximately 62.93 atomic mass units (u), and the atomic mass of Cu-65 is approximately 64.93 u.
To calculate the average atomic mass, you can use the following formula:
Average atomic mass = (Abundance of Cu-63 * Atomic mass of Cu-63) + (Abundance of Cu-65 * Atomic mass of Cu-65)
Plugging in the values, we get:
Average atomic mass = (0.6917 * 62.93 u) + (0.3083 * 64.93 u) = 43.47 u + 19.98 u = 63.45 u
Therefore, the average atomic mass of copper (Cu) is approximately 63.45 atomic mass units (u).