What is defined as the mass of one mole of a compound?

The mass of one mole of a compound is defined as its molar mass. Molar mass is the sum of the atomic masses of all the atoms present in a molecule, expressed in grams per mole (g/mol). This value is derived from the periodic table, where each element's atomic mass is listed.

When you calculate molar mass, you multiply the atomic mass of each element by the number of times that element appears in the compound. For example, for water (H2O), you would calculate the molar mass by adding together the masses of two hydrogen atoms and one oxygen atom.

This concept is essential in stoichiometry, as it allows chemists to relate the mass of a substance to the number of moles, helping to facilitate reactions and conversions between substances in a chemical equation.

Other terms, such as atomic weight, elemental mass, and molecular weight, do not specifically refer to the mass of one mole of a compound, making molar mass the correct and most precise choice in this context.