Molecular Weight

Name:
Molecular Weight
Detailed information:
The sum of the atomic weights of the atoms in a molecule. That of methane (CH₄) is 16.043, the atomic weights being carbon = 12.011, hydrogen = 1.008. The chemical formula used in such a calculation must be the true molecular formula of the substance designated. For example, the molecular formula of oxygen is O₂ and its molecular weight is 31.998 (atomic weight of oxygen = 15.999). For ozone the molecular formula is O₃ and the molecular weight is 47.997. The true molecular weight of a gas or vapor is found by measuring the volume of a given weight and then calculating the weight of 22.4 L at 0C and 760 mm Hg. The molecular weight of many complex organic molecules runs as high as a million or more (proteins and high polymers).See Avogadro; Atomic Weight; Mole.