PPT Slide

Molecular Masses from Chemical Formulas

• The molecular mass (aka. molecular weight) of a formula  unit of the compound is the sum of the atomic masses: molecular mass = sum of atomic masses in formula

The molecular mass of a water molecule ( 4 sig. figures) is (2 x atomic mass of H) + (1 x atomic mass of O) = (2 x 1.008 amu) + 16.00 amu = 18.02 amu

Molecular (or formula) mass of Ba(NO3)2=

(1 x at. mass of Ba)+(2 x at. mass of N)+(6 x at. mass of O)= 137.3 amu + (2 x 14.01 amu) + (6 x 16.00 amu)

= 261.3 amu

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