Definition. Gram molecular mass is the mass in grams of one mole of a molecular substance. Gram molecular mass is the same as molar mass. The only difference is that gram molecular mass specifies the mass unit to be used. Gram molecular mass may be reported in grams or grams per mole (g/mol). The mole is related to the mass of an element in the following way: one mole of carbon-12 atoms has 6.02214076 × 10 23 atoms and a mass of 12 grams. In comparison, one mole of oxygen consists, by definition, of the same number of atoms as carbon-12, but it has a mass of 15.999 grams. Oxygen, therefore, has a greater mass than carbon. A C 60 molecule is nonpolar, but its molar mass is 720 g/mol, much greater than that of Ar or N 2 O. Because the boiling points of nonpolar substances increase rapidly with molecular mass, C 60 should boil at a higher temperature than the other nonionic substances. The predicted order is thus as follows, with actual boiling points in parentheses: molecular weight, mass of a molecule of a substance, based on 12 as the atomic weight of carbon -12. It is calculated in practice by summing the atomic weights of the atoms making up the substance’s molecular formula. The molecular weight of a hydrogen molecule (chemical formula H 2) is 2 (after rounding off); for many complex organic atomic mass is the mass of an atom in atomic mass units. Again, it's a mass of a single atom. Molar mass is a mass (in grams) of a mole of atoms or compound. Expressed in grams per mole. It just so happens numerally it has the same absolute value as the atomic mass. I find molar mass more practical, and atomic mass is only needed to understand Strictly speaking, molar mass also refers to the mass (in kilograms) per mole of a substance, as opposed to its weight in grams. It is one of several other ways to express a substance’s inherent mass. In this case, it is the ratio between the substance’s molar mass and its atomic or molecular (formula) weight. Molar Mass = mass/mole = g/mol. The empirical formula mass of a covalent compound may be compared to the compound’s molecular or molar mass to derive a molecular formula. Combustion Analysis When a compound containing carbon and hydrogen is subject to combustion with oxygen in a special combustion apparatus all the carbon is converted to CO 2 and the hydrogen to H 2 O The molar mass is defined as the mass of a given substance divided by the amount of a substance, is expressed in grams per mol (g/mol). That makes the molar mass an average of many particles or molecules, and the molecular mass the mass of one specific particle or molecule. The molar mass is usually the more appropriate quantity when dealing The molar mass of an element is the mass in grams of one mole of the element. It is determined by writing its atomic weight on the periodic table in grams/mol. For example, the atomic weight of hydrogen to seven significant figures is 1.00794 amu, therefore, its molar mass to seven significant figures is 1.00794 g/mol. As with Ar, Mr is also a dimensionless quantity. It can be calculated as the sum of the relative atomic masses of the constituent elements. M - molar mass - this is the mass of a substance (m) divided by the amount of substance (n) and therefore has units of g/mol. I can be calculated as Ar (for atoms) or Mr (for molecules) multiplied by 1 g d19X3z.