To determine the weighted average atomic mass of Copper (Cu), we need to consider the masses and relative abundances of its isotopes, Cu-63 and Cu-65.
Here are the steps to calculate it:
1. Identify the given data:
- Abundance of Cu-63: [tex]\( 69.17\% \)[/tex] or [tex]\( 0.6917 \)[/tex] (in decimal form)
- Mass of Cu-63: [tex]\( 62.9296 \)[/tex] atomic mass units (amu)
- Abundance of Cu-65: [tex]\( 30.83\% \)[/tex] or [tex]\( 0.3083 \)[/tex] (in decimal form)
- Mass of Cu-65: [tex]\( 64.927 \)[/tex] amu
2. Calculate the contribution of each isotope to the weighted average:
- Contribution of Cu-63: [tex]\( 0.6917 \times 62.9296 \)[/tex]
- Contribution of Cu-65: [tex]\( 0.3083 \times 64.927 \)[/tex]
3. Perform the multiplication for each isotope:
- For Cu-63: [tex]\( 0.6917 \times 62.9296 \approx 43.5449 \)[/tex]
- For Cu-65: [tex]\( 0.3083 \times 64.927 \approx 19.9995 \)[/tex]
4. Sum the contributions to find the weighted average atomic mass:
- Weighted average atomic mass [tex]\( = 43.5449 + 19.9995 \approx 63.5454 \)[/tex] amu
Therefore, the weighted average atomic mass of the two Copper isotopes is approximately [tex]\( 63.5454 \)[/tex] amu.
