Question

Silver has two isotopes, 10747ag, which has a mass of 106.905 amu and a percent abundance of 52.00%, and 10947ag, which has a mass of 108.905 amu and a percent abundance of 48.00%. what is the atomic mass of silver?

Answer 1

The atomic mass of an element is a result of the weighted average of the masses of its corresponding isotopes. 

We are given: 
Ag-107: mass of 106.905 amu, 52 percent abundance 
Ag-109: mass of 108.905 amu, 48 percent abundance 

To be able to calculate the atomic mass of silver, we multiply the percent abundances of the isotopes by their respective atomic masses. Then, we add,

Atomic mass = (Atomic Mass of Ag-107) (% Abundance) + (Atomic Mass of Ag-109) (% Abundance )

Substituting the given values, we have

Atomic mass = 106.905 (.52) + 108.905 (.48)
Atomic mass = 107.865 amu

Therefore, the atomic mass of silver would be 107.865 amu.