<span> The </span>formula mass<span> is calculated by adding up all the atomic </span>masses <span>for every atom in the </span>formula<span>. First, we need to know the atomic masses of the atoms involved.
H = 1.01 amu S = 32.06 amu
Formula mass = 2 x </span>1.01 amu + 2 x 32.06 amu = 66.14 formula mass unit
