Algonquin College Health Program Assessment (AC-HPAT) Practice Exam

Which of the following correctly describes the relationship between empirical and molecular formulas?

1. Empirical formulas represent the same structure as molecular formulas

2. Empirical formulas are always more complex than molecular formulas

3. Molecular formulas can be derived from empirical formulas

4. Molecular formulas do not relate to empirical formulas

The correct answer is: Molecular formulas can be derived from empirical formulas

The correct answer highlights the fact that molecular formulas can be derived from empirical formulas, which is a key concept in chemistry. An empirical formula represents the simplest whole-number ratio of elements in a compound, while a molecular formula gives the actual number of each type of atom in a molecule. For example, if the empirical formula of a compound is CH2, this indicates that for every carbon atom, there are two hydrogen atoms. However, the molecular formula might be C6H12, which shows that the compound consists of six carbon atoms and twelve hydrogen atoms. In this case, the molecular formula is a multiple of the empirical formula (specifically, it is six times the empirical formula). Understanding this relationship is essential for interpreting chemical formulas and performing calculations in chemistry. It allows scientists to derive more specific information about a molecule's structure and composition based on the simpler empirical representation.