Question

A 7.36 g sample of copper is contaminated with a additional 0.51 g sample of zinc. suppose an atomic mass measurement was performed on this sample. What would be the measured atomic mass?

Answer 1

The average molecular weight of the mixture can be calculated using this formula:
MWav = x1MW1 + x2MW2

Where x is the mass fraction of the components of the mixture, in this case, copper (63.546 g/mol) and zinc (65.38 g/mol).

x1 = 7.36 / (7.36+0.51)=0.935
x2 = 0.51 / (7.36+0.51)=0.065

So,
MWav = 0.935(63.546) + 0.065(65.38) = 63.665 g/mol