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Molar mass is the mass (in grams) of one mole of a substance, typically expressed in grams per mole (g/mol). It is calculated by finding the sum of the atomic masses of all the atoms in a molecule. Empirical formula mass, on the other hand, is the mass of the simplest whole number ratio of elements in a compound, also expressed in g/mol. It is calculated by finding the sum of the atomic masses of the elements in the empirical formula.

The molar mass and empirical formula mass are the same when the empirical formula is the same as the molecular formula. In other words, when the compound already exists in its simplest whole-number ratio, the two masses will be equal. Examples of such compounds include water (H鈧侽), carbon dioxide (CO鈧�), and sodium chloride (NaCl).

The molar mass and empirical formula mass are different when the molecular formula is a multiple of the empirical formula. This means that the molecular formula represents a compound with more than the simplest whole-number ratio of its elements. Examples of such compounds include glucose (C鈧咹鈧佲倐O鈧�) with an empirical formula of CH鈧侽 and benzene (C鈧咹鈧�) with an empirical formula of CH.

When the molar mass and empirical formula mass are different, the molar mass of the compound is usually a whole number multiple of the empirical formula mass. This is because the molecular formula is a multiple of the empirical formula. To find this whole number multiple, simply divide the molar mass by the empirical formula mass: \( \text{Whole-number multiple} = \dfrac{\text{Molar mass}}{\text{Empirical formula mass}} \) In conclusion, the molar mass and empirical formula mass of a compound can be the same or different based on the whole-number ratio of elements in the compound. When the empirical formula is the same as the molecular formula, the masses are the same; when it is not, the molar mass is a whole number multiple of the empirical formula mass.