Final answer:
The empirical formula is the simplest ratio of the elements in a compound, while the molecular formula shows the actual number of atoms in one molecule. Glucose's molecular formula is C6H12O6, but its empirical formula is CH2O. The molecular formula of metaldehyde is C8H16O4 with an empirical formula of CH2O, and they can sometimes be the same, such as in the cases of P4, H2O, and CO2.
Step-by-step explanation:
Understanding Molecular and Empirical Formulas
An empirical formula represents the simplest whole-number ratio of the elements in a compound, whereas the molecular formula shows the exact number of atoms of each element in a molecule of the compound. For instance, the molecular formula of glucose is C6H12O6, which indicates that one molecule of glucose contains 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms. However, this is not its empirical formula because it is not the simplest ratio, which is CH2O. The molecular formula of metaldehyde is found to be C8H16O4, given that it contains 8 carbon atoms, 16 hydrogen atoms, and 4 oxygen atoms. The empirical formula for metaldehyde would be CH2O, following the procedure of simplifying the ratio of atoms.
It's important to note that a compound's empirical formula can sometimes be the same as its molecular formula, especially if the molecular formula already represents the simplest whole-number ratio of the compound's constituent elements. Compounds such as P4 (white phosphorus), H2O (water), and CO2 (carbon dioxide) have empirical formulas identical to their molecular formulas. To determine a molecular formula from an empirical formula, we need to know the molar mass of the compound, as well as the molar mass of the empirical formula.