Mole of Molecules:
The mass of a mole of molecules of a substance is the molecular mass expressed within grams. For instance, the oxygen molecule (O2) has a molecular mass equal to 32.0 grams since each oxygen atom has a molecular mass of 16.0 grams. (Recall that to acquire the molecular mass, atomic masses of all atoms which appear in the formula are added.) CH4, are added, the total is 16 amu if the atomic masses of the carbon and four hydrogen atoms in methane. Thus, one mole of CH4 has a mass of 16 grams. The mass of a mole of molecules is known as the molar mass or GMW (gram molecular weight).