How do empirical formulas relate to molecular masses?

Empirical formulas provide the simplest ratio of elements in a compound, which can be used to calculate molecular masses.

The empirical formula of a compound represents the simplest whole number ratio of atoms of each element in the compound. It does not provide information about the actual number of atoms in a molecule, but it does give us a way to calculate the molecular mass.

To understand how empirical formulas relate to molecular masses, let's consider an example. The empirical formula of glucose is CH2O. This tells us that for every carbon atom in glucose, there are two hydrogen atoms and one oxygen atom. If we know the atomic masses of carbon (C), hydrogen (H), and oxygen (O), we can calculate the empirical formula mass. Carbon has an atomic mass of approximately 12, hydrogen has an atomic mass of approximately 1, and oxygen has an atomic mass of approximately 16. Therefore, the empirical formula mass of CH2O is 12 + (2*1) + 16 = 30.

The molecular mass of a compound is the sum of the atomic masses of all the atoms in a molecule of the compound. For glucose, which has a molecular formula of C6H12O6, the molecular mass is (6*12) + (12*1) + (6*16) = 180.

The relationship between the empirical formula and the molecular mass is that the molecular mass is a multiple of the empirical formula mass. In the case of glucose, the molecular mass (180) is six times the empirical formula mass (30). This is because the molecular formula for glucose shows that it contains six times as many of each type of atom as the empirical formula. Therefore, by knowing the empirical formula and the molecular mass, we can determine the actual number of atoms of each element in a molecule of the compound.