When different, how is the molar mass related to the empirical formula mass?

When the molar mass and empirical formula mass are different, the molar mass is a whole-number multiple of the empirical formula mass.

Here's a breakdown of the relationship:

The empirical formula represents the simplest whole-number ratio of atoms in a compound. The empirical formula mass is the sum of the atomic masses of the atoms in the empirical formula. The molecular formula represents the actual number of atoms of each element present in a molecule of the compound. The molar mass is the mass of one mole of a substance, equivalent to the molecular weight expressed in grams.

The relationship between the empirical formula, molecular formula, empirical formula mass, and molar mass can be summarized as follows:

• Molecular Formula = (Empirical Formula)_n
• *Molar Mass = n Empirical Formula Mass**

Where 'n' is a whole number (1, 2, 3, etc.).

Example:

Let's consider glucose.

• The empirical formula of glucose is CH₂O.
• The empirical formula mass of CH₂O is approximately 12 (C) + 2(1) (H) + 16 (O) = 30 g/mol.
• The molecular formula of glucose is C₆H₁₂O₆.
• The molar mass of C₆H₁₂O₆ is approximately 6(12) (C) + 12(1) (H) + 6(16) (O) = 180 g/mol.

In this case, the molar mass (180 g/mol) is six times the empirical formula mass (30 g/mol). Therefore, n = 6.

In summary: If the molar mass and the empirical formula mass are different, you can find the whole number 'n' by dividing the molar mass by the empirical formula mass. This number, 'n,' indicates how many times the empirical formula repeats to form the actual molecular formula.