The element silver has an atomic weight of 108 and consists of two stable isotopes silver-107 and silver-109. The isotope silver-107 has a mass of 107 amu and a percent natural abundance of 51.8 %. The isotope silver-109 has a percent natural abundance of 48.2 %. What is the mass of silver-109

109

Explanation:

Let silver-107 be isotope A

Let silver-109 be isotope B

Let silver-107 abundance be A%

Let silver-109 abundance be B%

The following data were obtained from the question:

Atomic weight of silver = 108

Mass of isotope A (silver-107) = 107

Abundance of isotope A (silver-107) = 51.8%

Abundance of isotope B (silver-109) = 48.2%

Mass of isotope B (silver-109) = ?

Now, we shall determine the mass silver-109 as follow:

Atomic weight = [ (Mass of A x A%) / 100] + [ (Mass of B x B%) / 100]

108 = [ (107 x 51.8) / 100] + [ (Mass of B x 48.2) / 100]

108 = 55.426 + (Mass of B x 0.482)

Collect like terms

Mass of B x 0.482 = 108 - 55.426

Mass of B x 0.482 = 52.574

Divide both side by 0.482

Mass of B = 52.574/0.482

Mass of B = 109

Therefore, the mass of silver-109 is 109.