To find the total mass of the reactants, we need to add up the atomic masses of all the atoms involved in the reaction.
FeCl3: The atomic mass of Fe is 56 amu, and there are three Cl atoms with an atomic mass of 35 amu each. Adding these together, we get: 56 amu + (3 x 35 amu) = 56 amu + 105 amu = 161 amu.
H2O: The atomic mass of H is 1 amu, and there are two H atoms in H2O. The atomic mass of O is 16 amu. Adding these together, we get: (2 x 1 amu) + 16 amu = 2 amu + 16 amu = 18 amu.
Finally, we need to add the masses of FeCl3 and H2O together: 161 amu + 18 amu = 179 amu.
So, the total mass of the reactants is 179 amu.
Therefore, the correct answer is: 179 amu.