Molar mass Molar mass In chemistry, the molar mass "M" is a physical property defined as the mass of a given substance (chemical element or chemical compound) divided by the amount of substance. The base SI unit for molar mass is kg/mol. However, for historical reasons, molar masses are almost always expressed in g/mol. In simple terms, molar mass of a substance is the total weight of that substance (in either kilogram or gram) for one mole of that substance. That is, the weight of a substance for 6.02214076×10^23 molecules or atoms of that substance. As an example, the molar mass of
Epoxy the ratio of the amount of substance of epoxide groups, "n"(EP), and the mass "m"(B) of the material B, with the SI unit "mol/kg", or the so-called "epoxide equivalent weight", which is the ratio of the mass of a sample B of the resin and the amount of substance of epoxide groups present in that sample B, with the SI unit "kg/mol". The so-called "epoxide equivalent weight" is simply the inverse of the so-called "epoxide number". The specific amount of substance of epoxide groups is used to calculate the mass of co-reactant (hardener) to use when curing epoxy resins. Epoxies