* Identify the elements: Ammonium ion consists of nitrogen (N) and hydrogen (H).
* Find the atomic masses:
* Nitrogen (N): 14.01 amu
* Hydrogen (H): 1.01 amu
* Multiply the atomic mass of each element by its subscript in the formula:
* Nitrogen: 14.01 amu * 1 = 14.01 amu
* Hydrogen: 1.01 amu * 4 = 4.04 amu
* Add the results together: 14.01 amu + 4.04 amu = 18.05 amu
Therefore, the formula mass of the ammonium ion (NH₄⁺) is 18.05 amu.
