Question

What can we tell about a compound when we know the empirical formula? What additional information is conveyed by the molecular formula? By the structural formula? Explain in each case.

Short answer

The empirical formula represents the simplest whole number ratio of elements in a compound, showing the presence and simplified ratio of its elements. The molecular formula provides the actual number of atoms of each element in a molecule and its molecular mass. Meanwhile, the structural formula not only gives the actual number of atoms but also the arrangement and type of chemical bonds between them, crucial for understanding properties and reactivity. For hydrogen peroxide, its empirical formula is HO, molecular formula is H2O2, and structural formula is O-H | O-H.

Step-by-step solution

Empirical Formula

An empirical formula represents the simplest whole number ratio of elements in a compound. It shows which elements are present and the most simplified ratio between them. However, it does not provide information about the molecular mass or the actual number of atoms of each element in a molecule of the compound. For example, the empirical formula for hydrogen peroxide is HO, indicating that in this compound, the ratio between hydrogen and oxygen atoms is 1:1.

Molecular Formula

Molecular formulas provide additional information compared to empirical formulas. They show the actual number of atoms of each element in a molecule of the compound. It provides information about the molecular mass, as it represents the total number of atoms, but it does not give any details about the arrangement of atoms or structure of the compound. Using the hydrogen peroxide example, its molecular formula is H2O2, which tells us that one molecule of hydrogen peroxide contains 2 hydrogen atoms and 2 oxygen atoms.

Structural Formula

The structural formula provides the most information about a compound among the three types of formulas discussed. It shows not only the actual number of atoms of each element but also the arrangement of these atoms and the type of chemical bonds between them. It helps understand the spatial organization and the functional groups present in the compound, which are crucial for understanding the compound's properties and reactivity. In the case of hydrogen peroxide, the structural formula is: O-H | O-H This tells us that in a hydrogen peroxide molecule, each hydrogen atom is bonded to an oxygen atom, and the two oxygen atoms are bonded together. In summary, the empirical formula provides the simplest ratio of elements in a compound, the molecular formula gives the actual number of atoms of each element in a molecule of the compound, and the structural formula provides information about the arrangement and bonding of atoms.