Find formula unit mass of NaHCO3?

84.0 amu

Formula mass unit is the sum of all the atomic weights that make up the substance.

In the case of ##NaHCO_3##, you need to count first how many atoms are there in the formula.

Na = 1 H = 1 C = 1 O = 3

Next is to get the atomic weights (just take a look at the periodic table).

Atomic weight of Na = 22.989769 amu (atomic mass unit) Atomic weight of H = 1.00794 amu Atomic weight of C = 12.0107 amu Atomic weight of O = 15.9994 amu

Then add the atomic weights according to the formula. 22.989769 amu + 1.00794 amu + 12.0107 amu + (3 x 15.9994 amu)

= 84.0 amu