Formula unit mass Atomic mass of C a2atomic mass of C l 4071 111 Answer verified by Toppr 4 Views Upvote 56. There is a difference between them. Because a proper formula is electrically neutral with no net electrons gained or lost the ions can be considered atoms for the purpose of calculating the formula mass.
Each and every atom has a mass given by amu units.
A formula unit in chemistry is the analytical formula used as a separate body for stoichiometric measurements of any ionic or covalent network solid compound. The formula for iron II sulfate is FeSO4H2O and its gram formula unit mass is 16992. The formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in the empirical formula. Therefore 352 formula units of this compound have a mass of 598 grams to the justified number of significant digits.