To determine the mass of Ag-109, we need to know the difference in mass between Ag-107 and Ag-109. The difference in mass between isotopes is equal to the atomic mass unit (amu) value of Ag-109 minus the amu value of Ag-107.
Given that the mass of Ag-107 is 106.905 amu, we can subtract this value from the atomic mass unit (amu) value of Ag-109 to find the mass difference:
Mass difference = Atomic mass of Ag-109 - Atomic mass of Ag-107
Since Ag-109 has a greater atomic mass than Ag-107, we can express this as:
Mass difference = Mass of Ag-109 - Mass of Ag-107
However, without the specific atomic mass unit value for Ag-109, it's not possible to calculate the exact mass of Ag-109. The atomic mass of Ag-109 must be provided in order to determine its mass accurately.