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 epoxy resins is the epoxide group content. This is correctly expressed as the specific amount of substance of epoxide groups in the material B under consideration, calculated as the ratio of the amount of substance of epoxide groups in this material B, "n"(EP), divided by the mass "m"(B) of the material B under consideration, in this case, the mass of the resin. The SI unit for this quantity is "mol/kg", or multiples thereof. Deprecated quantities which are still in use are the so-called "epoxide number" which is (not a number and should therefore not be referred to as such, but)