University:
Hunter College CUNY
Course:
CHEM 106 | General Chemistry Laboratory
Academic year:

2023
Views:

274

Pages:

1
Author:

tisz1tivsz20

The weight-formula and the molecular mass If we add the masses of the atoms of the chemical formula of a compound we obtain its formula weight. If the formula also represents a real molecule, we can talk about molecular mass. To calculate the weight-formula of a compound we need the periodic table, where the atomic weights of all the chemical elements are collected. Example 1 Sodium bicarbonate: 𝑁𝑎𝐻𝐶𝑂3 Formula weight = 23.0 + 1.0 + 12.0 + 3 ⋅ 16.0 = 84.0 uma In this case the formula represents a crystal lattice, but not a molecule. Example 2 Water: 𝐻2 𝑂 Formula weight = 2 ⋅ 1.0 + 16.0 = 18.0 uma Since the formula does represent a real molecule, we can say that the molecular mass of water is 18.0 amu.

Exam Solutions Molecular Mass

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