To find the total mass of the reactants, we need to add up the individual masses of each atom in the reactants.
FeCl3 has one Fe atom with a mass of 56 amu and three Cl atoms with a mass of 35 amu each. This gives a total mass of FeCl3 as 56 amu + (3 x 35 amu) = 56 amu + 105 amu = 161 amu.
H2O has two H atoms with a mass of 1 amu each and one O atom with a mass of 16 amu. This gives a total mass of H2O as (2 x 1 amu) + 16 amu = 2 amu + 16 amu = 18 amu.
Adding the total masses of FeCl3 and H2O together gives 161 amu + 18 amu = 179 amu.
Therefore, the total mass of the reactants is 179 amu.